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Thread: Old problem new view!

  1. #1
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    Old problem new view!

    So ive been battling a stumbly bucking hesitant acceleration for some time. Today i found the trick to my dme. I have to press the pedal 5x again to see the next code. I got 1215, 1216, 1221. MAF, TPS, and O2 respectively.
    Of course the o2 code is because it runs lean as it can go without pinging. The o2 sensor is brand new. But why would i get both a MAF and TPS code.? The engine doesn't benefit from either being disconnected or swapped with other ones i have.

    Could a bad fuel pump cause this? a bad thermostat?


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    Last edited by snow663; 04-17-2017 at 10:47 PM.

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    Have you inspected the wiring harness at the top of the firewall in the engine bay? Expose all those wires and examine them.

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    Old problem new view!

    Quote Originally Posted by Eric93se View Post
    Have you inspected the wiring harness at the top of the firewall in the engine bay? Expose all those wires and examine them.
    Ive visually inspected them. Everything 'looks' fine i know that means jack shit. But ive tested the tps and maf wiring before and its fine.
    Also what is the operating temp of this engine? Ive read 90*c... I have the aluminum t-stat housing and i used an infrared thermometer on it after driving 20 miles to work. 67*c thats kind of a big difference and would definitely cause it to run rich which would account for fouling my plugs leading to power loss correct?


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    Last edited by snow663; 04-18-2017 at 04:10 PM.

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    Quote Originally Posted by snow663 View Post
    Also what is the operating temp of this engine? Ive read 90*c... I have the aluminum t-stat housing and i used an infrared thermometer on it after driving 20 miles to work. 67*c thats kind of a big difference and would definitely cause it to run rich which would account for fouling my plugs leading to power loss correct?

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    It is 90 C but you can't trust a reading of a regular IR thermometer on aluminum. They come calibrated for an emissivity of 0.95 while cast aluminum is well under 0.5 (probably closer to 0.09 depending on surface finish) which will bugger your reading. Anodized aluminum is around 0.77 which will be much closer at least.

    Remember, an IR thermometer is just a fancy light meter, and it's hard to measure how much light a surface is giving off vs reflecting when you don't know how shiny it is, and infra-red is just light!

    Source: http://www.engineeringtoolbox.com/em...nts-d_447.html
    Caprica Junkie

  5. #5
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    Old problem new view!

    Quote Originally Posted by boarder2k7 View Post
    It is 90 C but you can't trust a reading of a regular IR thermometer on aluminum. They come calibrated for an emissivity of 0.95 while cast aluminum is well under 0.5 (probably closer to 0.09 depending on surface finish) which will bugger your reading. Anodized aluminum is around 0.77 which will be much closer at least.

    Remember, an IR thermometer is just a fancy light meter, and it's hard to measure how much light a surface is giving off vs reflecting when you don't know how shiny it is, and infra-red is just light!

    Source: http://www.engineeringtoolbox.com/em...nts-d_447.html
    So how would i accurately measure the temp then. I measured a dirty surface not polished up so i would assume the grime on the housing is as hot as the housing minus a degree or two. I mean its kinda obvious its running cold now that i look at it. Say i get to work and park. Sit in idle for a minute the heater cools down. Doesn't get cold but gets noticeably cooler.
    I already ordered a t-stat and an coolant temp sensor for the hell of it since ill be in there.

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    Last edited by snow663; 04-18-2017 at 09:04 PM.

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    Old problem new view!

    Ok new T-stat, and CTS, still no luck. It warms up quicker but the needle stays in the same spot. And heater stays warmer at idle. But it didn't affect performance much. If you let er rip in 1st or 2nd it bucks and hesitates all the way up to red line. Feels like im bad with a ckutch but no matter how easy you clutch it as soon as the engine is under full load it starts bucking.
    After about 5k i feel a drop in power and it just feels slow.
    If you floor it it loses power and feels slow.
    The only time it accelerates smoothly is if you keep the throttle low but even then you can feel a steady hesitation like im pulling a loaded trailer. If you give it more gas itll go faster but not like it should.
    At idle it will miss one cylinder every 45 seconds to a minute apart. (Slight pop or put)
    AFR gauge shows lean in all conditions except idle. At idle itll hold 14.7 perfectly

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    Last edited by snow663; 04-21-2017 at 08:57 PM.

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    Have you any idea on what the intake temperature is being read as? I don't really know whether the Intake Air Temperature Sensor (IAT, located at the back of the manifold) plays a major role in setting the mixture, but that would seem to be the next logical step if you've tried swapping other components.

    A fueling issue could be the culprit; do you know when the fuel filter was last changed? If its considerably blocked, you could have a fuel starvation issue outside of idle. Could also be injectors, or even inadequate fuel pressure (there is a means of testing this, BTW).

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    Old problem new view!

    Quote Originally Posted by B320i View Post
    Have you any idea on what the intake temperature is being read as? I don't really know whether the Intake Air Temperature Sensor (IAT, located at the back of the manifold) plays a major role in setting the mixture, but that would seem to be the next logical step if you've tried swapping other components.

    A fueling issue could be the culprit; do you know when the fuel filter was last changed? If its considerably blocked, you could have a fuel starvation issue outside of idle. Could also be injectors, or even inadequate fuel pressure (there is a means of testing this, BTW).
    Its under the back of the mani, could be oil contaminated there is oil in the manifold im assuming from the pcv system. But idk if that would throw it off?? Its been changed and tested within spec.

    Fuel filter is a year old
    Injectors have been swapped twice
    Fuel Pressure at idle is fine 43 psi, With the regulator disconnected 51 psi. Tests the same at the pump as it does at the rail.

    I noticed when the engine is cold at any throttle more than just idle when under load causes a loss of power. And my wideband goes clear up to 18:1 till i give it more throttle then itll go up to 14:1. I am not getting WOT enrichment either. So i believe its running lean like the tune is off.

    It "feels like" The DME cant calculate load properly on throttle tip in and it fuel starves for a second before reverting to a default map and gaining power again without throwing a CEL
    I have two MAFs and both make the car feel different but not better.
    When its cold on the first time rolling in gear for the day it will lag really bad. And my power loss is proportional to throttle. More throttle=more power loss to the point where i think its died and my afr goes way lean then right as im about to let off thinking it died itll just snap out of it and go like hell cuz i got the pedal almost to the floor.
    The second MAF i have came from Chris off this forum. Out of a parts car so idk if its any good. Could i just have two bad MAFs?

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    Last edited by snow663; 04-22-2017 at 01:35 AM.

  9. #9
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    Old problem new view!

    Compression is good, 173-180psi in 5 strokes
    Fuel pressure is good, 43-51psi
    Injectors are good, (swapped 6 reman)
    Coils/boots/plugs are good. (Swapped with 6 NEW coils and boots) tried different kinds/brands/material plugs and tried a smaller gap on som cheap autolites.
    That rules out the engine itself and fuel delivery system/ignition
    Smoked for vac leaks its good. Vacuum is 18" no flux, that's perfect so its not cam timing or valves. Also rules out exhaust.
    Virtually all the sensors test good. Tested from the ECU harness plug. And all have been replaced With the exception of MAF, and CamPS, because i lack the equipment to test them, these are digital sensors that put out frequencies. I do not have an oscilloscope. But ive swapped the camPS back and forth with no difference..... that leaves us with a maf that ive substituted an unknown used replacement for and got negligible results.

    Is my diagnostic process good enough to say i should bite the bullet and get a MAF $130 for the probe $200 for the whole assembly at my local autozone.

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    Last edited by snow663; 04-22-2017 at 02:03 AM.

  10. #10
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    If everything tests good; you've tried different sensors to try and eliminate the problem and have even tried running without some connected. Almost sounds like your DME could be the culprit here. Might be worth opening it up and inspecting for any signs of moisture (water ingress) damage, and finding a known-good spare you can test out.

  11. #11
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    Old problem new view!

    Quote Originally Posted by B320i View Post
    If everything tests good; you've tried different sensors to try and eliminate the problem and have even tried running without some connected. Almost sounds like your DME could be the culprit here. Might be worth opening it up and inspecting for any signs of moisture (water ingress) damage, and finding a known-good spare you can test out.
    The only other bmw available has the non vanos engine so id have to buy an ebay one to rule out the DME. But i have looked inside the DME. It looks like its brand spanking new like it hasnt seen the light of day since it was born.


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    Why don't you just unplug the maf and see if there is an immediate improvement? It's called the disconnect test and it's been around for years. Works quickly like a charm especially when the problems are more obvious, and is quick and reversible easily: http://www.bimmerfest.com/forums/sho...d.php?t=882501

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    Old problem new view!

    Quote Originally Posted by ilikemycar View Post
    Why don't you just unplug the maf and see if there is an immediate improvement? It's called the disconnect test and it's been around for years. Works quickly like a charm especially when the problems are more obvious, and is quick and reversible easily: http://www.bimmerfest.com/forums/sho...d.php?t=882501
    Ive tried it. The car still struggles in open loop with no MAF, also tried unplugging o2 and TPS independently. 1 sensor at a time.

    Ps.. the thermostat was running it cold. After replacing the t-stat and temp sensor my infrared thermometer reads 190* on the dot from the upper rad hose 206 from the lower. And my idle vibration went away. Im assuming it was running rich and fouled the plugs. Now its running way cleaner. Exhaust smells better.

    I am still getting a TPS code. Ohm test shows a smooth resistance change but the resistance across the two outer pins is 3.75kohm the book specs approx 4kohm. Is that bad? Thats like 5% tolerance like most pots so should be fine this code may be related to me unplugging the sensor. No matter what the total resistance is these pots are used as a voltage divider. So 5% tolerance would be okay in my mind. A 1k pot vs a 10k pot would both put out 2.5v at 50% with a 5v reference.

    Im starting to think this is a fuel delivery issue. Low volume because idle pressure is fine. But my problem is under load. Also my problem exists in open loop. Smells rich and feels doggy till you give it more air. Once it hits closed loop it leans way out and loses power. Wide open at 13.5:1.


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    Last edited by snow663; 04-22-2017 at 11:32 PM.

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    Old problem new view!

    Fuel pressure is in spec at idle. But with the engine off pump jumpered at the relay it makes a lot of noise. The pump is very audible and you can hear a percolating sound at the fuel pressure regulator end of the rail. https://youtu.be/_2S2_z07Ofs
    The pump pulls 4.76A the book says 5A max. https://youtu.be/FZdgHnoFVlA
    Pressure bleeds off quickly back through the pump. So the pump check valve is bad. Will that cost performance at all?

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    Last edited by snow663; 04-23-2017 at 09:31 PM.

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    Hi Snow,


    Running out now so a quick reply. The disconnect test should be done on all dtiveability sensors, even those not on the suspect list. It should especially be done on the cts. Please do that right away.


    If that doesn't help consider that
    you may have more than one sensor damaged. It can cause funny symptoms.


    Do this. Disconnect both the tps and the maf. Start the engine, give it 3 minutes to stabilize if there's a rough idle, then test the car under conditions that caused this issue.


    If the problem remains, them I'm willing to gamble that its the o2 sensors or the circuitry. Unplug all the o2 sensors - easy job since its just near the fuel rail. Reconnect the good maf and tps. Then retest. If the problem remains, leave the sensors unplugged and disconnect the maf. Retest. If the problem remains, reconnect the maf, disconnect the tps, retest. If the problem remains, disconnect both together with the o2 sensors. Retest.


    This will take you 15-20 minutes. Far better than speculating here. Test test test.


    And delete codes at the end of all of that.

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    Could there be a leak in the pump pickup? Causing the fuel in the rail to have air bubbles in it? It should be a nice smooth sound. I had a Nissan with a bad check valve at the fuel pump and pressure would drop immediately when the pump stopped, it just cranked a little extra when starting until pressure built up.
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    Quote Originally Posted by jc43089 View Post
    Could there be a leak in the pump pickup? Causing the fuel in the rail to have air bubbles in it? It should be a nice smooth sound. I had a Nissan with a bad check valve at the fuel pump and pressure would drop immediately when the pump stopped, it just cranked a little extra when starting until pressure built up.
    When i first jump the pump at the relay it sounds smooth like water coming out of a slightly cracked faucet. Then a couple seconds in and it sounds like theres air bubbles in it like the fuel is aerated.


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  18. #18
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    Quote Originally Posted by ilikemycar View Post
    Hi Snow,


    Running out now so a quick reply. The disconnect test should be done on all dtiveability sensors, even those not on the suspect list. It should especially be done on the cts. Please do that right away.


    If that doesn't help consider that
    you may have more than one sensor damaged. It can cause funny symptoms.


    Do this. Disconnect both the tps and the maf. Start the engine, give it 3 minutes to stabilize if there's a rough idle, then test the car under conditions that caused this issue.


    If the problem remains, them I'm willing to gamble that its the o2 sensors or the circuitry. Unplug all the o2 sensors - easy job since its just near the fuel rail. Reconnect the good maf and tps. Then retest. If the problem remains, leave the sensors unplugged and disconnect the maf. Retest. If the problem remains, reconnect the maf, disconnect the tps, retest. If the problem remains, disconnect both together with the o2 sensors. Retest.


    This will take you 15-20 minutes. Far better than speculating here. Test test test.


    And delete codes at the end of all of that.
    Ive tried all that. Tested all that, and replaced all that. Got me a few hp back but no go on the hesitation.


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  19. #19
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    Quote Originally Posted by snow663 View Post
    When i first jump the pump at the relay it sounds smooth like water coming out of a slightly cracked faucet. Then a couple seconds in and it sounds like theres air bubbles in it like the fuel is aerated.


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    Right, poke a hole in a straw above the height of liquid and try to drink from it. You will get aerated liquid. The pump is sucking the fuel through a tube in the tank and if the tube has any leaks it will suck air in as well. I'm not saying this is your problem but it shouldn't sound aerated by the FPR.
    '94 325i Sedan, Arctic Gray: UUC LTW FW, EVO 3 and DSSR, +.020 Maxsil pistons, ASC delete, Eibach shocks/springs, 16" contour reps 238k
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    '89 325i Vert, Alpine White: 5spd swapped. Sold
    '04 Toyota Sienna XLE Limited AWD, In progress swapping to M50/G250, http://www.wibimmers.com/board/index...nna-25i-build/
    '05 Volvo V70 R, 6mt, mostly stock, kid hauler 200k Sold
    '85 Toyota LandCruiser: Lifted, gas hog. 205k

  20. #20
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    Quote Originally Posted by jc43089 View Post
    Right, poke a hole in a straw above the height of liquid and try to drink from it. You will get aerated liquid. The pump is sucking the fuel through a tube in the tank and if the tube has any leaks it will suck air in as well. I'm not saying this is your problem but it shouldn't sound aerated by the FPR.
    Well since everything in the fuel system is new except the pump. And the pumps check valve is leaking the pressure out after shutdown, and its making a sound it definitely should not be making im going to replace it.

    The fuel pump, DME, IACV, and MAF are the only original parts to this engine left. And nothing thus far has given me any results. I have two mafs and neither fix it. So at this point its gotta be the fuel pump or the computer. It idles fine but loses power mid throttle. So its not iacv and i don't believe the computer is bad.


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  21. #21
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    If it was me I would find some clear tubing and hook it to the pump discharge, you would probably see the bubbles, and you can also do a volume test, just because the pump supplies pressure does not mean it is keeping up with volume.
    '94 325i Sedan, Arctic Gray: UUC LTW FW, EVO 3 and DSSR, +.020 Maxsil pistons, ASC delete, Eibach shocks/springs, 16" contour reps 238k
    '93 325is Coupe, Schwarz, work beater 299k
    '89 325i Vert, Alpine White: 5spd swapped. Sold
    '04 Toyota Sienna XLE Limited AWD, In progress swapping to M50/G250, http://www.wibimmers.com/board/index...nna-25i-build/
    '05 Volvo V70 R, 6mt, mostly stock, kid hauler 200k Sold
    '85 Toyota LandCruiser: Lifted, gas hog. 205k

  22. #22
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    Quote Originally Posted by jc43089 View Post
    If it was me I would find some clear tubing and hook it to the pump discharge, you would probably see the bubbles, and you can also do a volume test, just because the pump supplies pressure does not mean it is keeping up with volume.
    Yes!! Why didnt i think of that. See this is why i come here. I know what im doing but sometimes it pays to have two brains on it. Clear tubing would definitely let me see if there were bubbles in there.


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  23. #23
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    Any clear tubing will probably get wrecked by the fuel but who cares, you only need a couple feet. There should be a spec for how many GPM the pump flows without restriction too. You can time how long it takes to fill a gas can and calculate it.
    '94 325i Sedan, Arctic Gray: UUC LTW FW, EVO 3 and DSSR, +.020 Maxsil pistons, ASC delete, Eibach shocks/springs, 16" contour reps 238k
    '93 325is Coupe, Schwarz, work beater 299k
    '89 325i Vert, Alpine White: 5spd swapped. Sold
    '04 Toyota Sienna XLE Limited AWD, In progress swapping to M50/G250, http://www.wibimmers.com/board/index...nna-25i-build/
    '05 Volvo V70 R, 6mt, mostly stock, kid hauler 200k Sold
    '85 Toyota LandCruiser: Lifted, gas hog. 205k

  24. #24
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    Snow, just saw your video. My bad didn't notice that earlier. Thank you for doing that up. It helps.

    Yes the pump seems too noisy. But I'll come to that a bit later. First a soapbox piece.

    Gonna give you some advice. First, the job of troubleshooting is not to figure out exactly what is wrong. Frequently, that is not possible without sophisticated instruments, a helper, and alot more time than we usually have or want to deploy.. The job of troubleshooting is to get into the 90% probability box. That is, as long as we are 90% sure that it is a, b or c that's d,amaged we can stop troubleshooting and take action.

    In practice, that works more than 90% of the time. The car is not a very sophisticated engineering device when stacked against things like jets, space shuttles, etc. A 90% approach works very well, doesn't take too much time, doesn't cost too much, and is usually effective in solving the problem efficiently. We may be enthusiasts but the car is not meant to become our career.

    Trying to be 100% sure every time is not productive in our context.. So even when you're in the 10% box where your analysis turns out wrong, that's not you being dumb. That's just the understood limitation of the approach. Keep the car long enough, and you'll save enough time and money over many incidents with this 90% approach. You'll still come out ahead. So don't beat yourself up over that.

    Taking this 90% approach has lead me to discover and identify many quick and dirty methods of troubleshooting stuff quickly. One such method is the disconnect test that I found online years ago.

    Why the long preamble? I'm going to make a radical suggestion to you. I'm going to be asking you to throw parts at the problem. Some of them are new parts, to boot.

    ---------

    See my earlier post and test out all your driveability sensors including the coolant temp sensor. If that doesn't produce results, get a new oem pump for $150 and install that. Why ? Because we're not buying E36s because we are broke. We buy them because we are enthusiasts. And enthusiasts will change all the key parts of the car eventually anyway. The fuel pump is one such part. It has lasted 20 years. That's a good enough run. If it fails, it usually happens without warning and leaves you stranded literally anyway. Factor in the inconvenience, humiliation, the cost of a tow and repair etc and smart people change the pump ahead of time.

    So get a new pump and change it especially if the disconnect test proves fruitless. Even if the pump doesn't solve your current problem, it is a worthwhile investment in the car. And you knock out one well known no-start issue right out of the park permanently.

    My final thoughts at this point is that if it isn't the pump or the driveability sensor(s), it would likely be the ecu that's messing up the show.

    You need to have a spare ecu with you. Its an essential good used spare par that can always be resold later for the same price (around $60) if you ever sell the car. And you need to have the means to read the old ecu's ews code and transfer that to the new ecu. The software to do this is available for free and I believe was invented by a member of bfc. The hardware can be bought for $50 with a software cd, and you need that to run more sophisticated software like inpa and bmwdis on the car anyway. So these would be worthwhile investments.

    So if you go to all that trouble and it is not the ecu, you've not wasted your time and money because you've equipped yourself correctly to maintain the car in future anyway.

    So if the pump doesn't work, try the ecu. With a good used ecu, and a new pump, if the problem is not fixed, do the disconnect test again.

    If its not the sensors, the pump, or the ecu, it is you. You are doing some repair, observation, or diagnosis wrong. Again, this is not the space shuttle. There can only be so many things that could be wrong with it. At that point, you'll need to hire a mobile mechanic off craig's list. Fresh eyes would probably find the problem within 15 minutes or less. That's just the way it is.

    Just for the heck of it do this. Start the engine and shut down and leave the car for a few hours. Then yank the regulator's vacuum hose at the manifold end and sniff it. It should not smell of fuel. If it does, it is leaking, and bleeding off pressure somehow during driving. This takes 2 minutes in and out. Don't yank the hose at the regulator end. Sniffing that will only test for leaky injectors.

    And there is no pump check valve on cars with rail fuel pressure regulators. The regulator holds rail pressure to permit a startup following a shutdown, the way a check valve used to.
    Last edited by ilikemycar; 04-24-2017 at 05:03 PM.

  25. #25
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    Old problem new view!

    Quote Originally Posted by jc43089 View Post
    Any clear tubing will probably get wrecked by the fuel but who cares, you only need a couple feet. There should be a spec for how many GPM the pump flows without restriction too. You can time how long it takes to fill a gas can and calculate it.
    Says .9 quarts in 30 seconds from the outlet of the fuel rail so the spec is measured under pressure and yeah clear tubing doesn't last long with fuel. Discolors and hardens the hell out of it. But its only for test purposes its not like im gonna leave it in there.


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    Last edited by snow663; 04-24-2017 at 05:04 PM.

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