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Panic : yet another “my car dies while driving” post - suspects : FPR, fuel pump

I’m in a bit of panic here

Car died while driving twice today. first was 2nd or 3rd gear, 2000 RPMs. Started back up right away. Second was idle, 850 RPM. Had to mash the ignition a couple times. Both dry conditions, cool, engine warmed up mostly. Both stayed running fine til shutting engine off.

All solved here recently: Ignition cables, battery, alternator, alternator belt, distributor cap/rotor.

So I’m thinking fuel pump - I’ll check the pressure if I can locate my tester.


Last edited by Bukowski; 05-09-2019 at 09:12 AM.. Reason: trying to add clues as to the possible solution so this "my car died" thread might stand out...?
Old 05-01-2019, 02:08 PM
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After the fuel pump, check the fuel pressure regulator on the fuel rail. Clarks garage has a thorough step by step test procedure.

Good luck.
Old 05-01-2019, 03:46 PM
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This also happened after I wiggled gently the vacuum check valve. Perhaps irrelevant.

I read Clark’s, and seems if it was the pump, the engine wouldn’t run well in general.

Also FPD and FPR are ... well, possibly 10 years old - both replaced with new.
Old 05-01-2019, 05:05 PM
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Check DME relay....they are notorious for causing all sorts of power shut down gremlins....also ensure the bracket that holds all the relays in below glove box is fixed in and screwed down properly and that all the connecting wires at the back are not loose....this happened to me last year...twice as well....
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Old 05-02-2019, 08:56 AM
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Quote:
Originally Posted by mikseymono View Post
Check DME relay....
good call - just looked under the cap. looks in perfect condition. (pics to come if I solve this one)
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Old 05-02-2019, 11:19 AM
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also started it up and looked on top of the engine just now - no leaks from the FPD or FPR, injectors, or anything else that I could notice. Last time I replaced the damper, it was obviously leaking. I forgot how exactly I came to replace it in the first place... I never tested the pressure at that time.
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Old 05-02-2019, 11:20 AM
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Check what DME relay you have...you will want an OEM..or worst case URO 3rd gen....and then get a spare!

M
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Old 05-02-2019, 11:22 AM
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Quote:
Originally Posted by mikseymono View Post
Check what DME relay you have...you will want an OEM..or worst case URO 3rd gen....and then get a spare!

M
I just picked up the Focus 9 solid-state DME relay. A bit pricey, but much more confidence it won't go bad (ever). Works great so far. I mean, I still carry a spare, but that's just so I'm not tempting fate lol.

Also, check the speed/reference sensor plugs and wiring around them. That's what was causing my stalls/occasional hard start.
Old 05-02-2019, 05:29 PM
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alright, had another road test. not good.

cold idling, seems ok. took a ride - warming up, went maybe 1/2 mile, stalls - a descending running stall (in gear) - not sure if this means anything. Almost stalled a couple times, had to press the accelerator to keep it going - had a jerking motion, a sort of spitting sound from the tail pipe (no backfires). Really hard to make observations of this. Clearly, the stalls are rapidly increasing in frequency, just from the past few miles.

Tested the fuel pump by simply jumping the DME (that standard technique). It runs OK by listening to the flow in the lines, and I stopped it within a minute or two. However, starting the engine and letting it idle - after it is already warm - results in a stall within a couple minutes. Not obvious why. Vacuum is still there - the reservoir line makes a hiss noise if the line is detached. Vacuum lines look and feel connected ok. Some odors observed are slight, and hard to specify - perhaps unrelated. No obvious smoke from the engine bay. No leaks still.

I still need to get my fuel pressure gauge. However - if the pressure is in fact low, or the delivery rate is low, it would only mean the pump is wearing out. (Thinking this out here ): There is a complete stall of the engine - and it's revival upon restart (this is sort of reliable). While driving the car, the performance seems OK, and then the engine stalls - but the car can remain in gear and slow to a stop without strange problems.

Question - what fuel pressure could explain an engine stall?
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Old 05-03-2019, 08:32 AM
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here's a thread where URO argues for the improved design and manufacture of their DME relays :

Help something’s wrong
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Old 05-03-2019, 08:37 AM
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OK..feel your pain...

Have you checked the fuel pressure out at the rail as per Clarkes?
When did you last change the fuel filter?

You will get there in the end...I did....you just have to be methodical...Clarks proceedures are the way to go.

Bon courage!

M
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Old 05-03-2019, 08:38 AM
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OK cool, thanks.

thought I should add that I am PRETTY sure this is a Bosch fuel pump, and it has to be at least 15 years old, probably more. It even survived being out of the car for a couple years, then going back in for .. well, a few years.

yeah, I can check the pressure when I get my gauge, but I'm asking what fuel pressure on the Bosch specifically (this is a high quality pump) would explain a stall?

Fuel filter has to be approx. four years old
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Old 05-03-2019, 08:56 AM
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About a year ago, "Steeley90" on Rennlist was having a terrible time with several different brand DME relays (including OEM), and had this to say about URO Parts' new 3rd gen unit:


"After contacting Uro as per the reply on this thread, not one but two of their new relays were sent out to me. The parts arrived at my work and I swiftly made my way to the car park to try one out.

I wish I had a dash cam that had captured my face when the car started first time with the new relay installed. I'm absolutely ecstatic. I cannot value these new relays high enough. I've tried every other option of relay including Porsche OEM and none worked. It's still a luxury for me to get in the car and not have to pop the bonnet. One I'm sure I won't get tired of for a long time.

Thanks ever so much to the guys at URO, you've made this 944 owner the happiest guy!"



Glad we could help! Mikseymono also received one, but he hasn't had a chance to use it very much yet and we look forward to his feedback. If anyone else needs one, this 3rd gen relay is available from Pelican here (disregard the photo showing the 2nd gen relay, we'll ask Pelican to update it): https://www.pelicanparts.com/More_Info/993-615-227-01-M253&SuperCat=Y&SVSVSI=0794.htm
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Last edited by UROParts; 05-03-2019 at 09:08 AM..
Old 05-03-2019, 09:02 AM
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Took a sample of fuel from between the pump and the hose that attaches to the tank output - so from the fuel tank, through the strainer. Couple questions:

1. Fuel (87 Octane) is light tan. Has some particles.

2. Let fuel sit a while.I guess it evaporated a bit. Turns cloudy after a few hours.

I can get some pics but is the tan color not unexpected, and is the cloudiness unexpected?

I’ll report back if I see evidence of moisture precipitating out of the fuel - a drop of water at the bottom of the fuel. Because I think that is what is happening here.
Old 05-06-2019, 01:58 PM
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UPDATE : the droplet in the fuel is probably just ethanol! not water! Will try a fresh test to confirm.
ANOTHER UPDATE : the droplet is probably water, not ethanol because fresh fuel does not give the same result - fresh fuel stays in one phase.

fuel sample after drawing from the tank-to-fuel-pump hose:


fuel sample from above after sitting in cool, dry air for 3-5 hours and swirling. Did not wait very long after swirling :


... next I'm looking at drain ports around the gas cap, the gas cap itself, and the integrity of the fuel filler neck. It seems OK from the outside - tight. Drain ports appear clogged.

but I suppose it is likely water got by the seals there. I'm not sure how it could be dissolved in the fuel so well... puzzling.

but I think the next thing to do is drain and flush the tank out.
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Last edited by Bukowski; 05-09-2019 at 10:27 AM.. Reason: updated interpretation of droplet - probably just ethanol - ANOTHER update - it's probably water!
Old 05-06-2019, 04:19 PM
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If a fuel tank is partially empty for long periods, humidity in the air above the gas can condense every night as temperature drops and sink to the bottom of the tank. No one likes to keep a full tank in a project car (because it's that much more fuel that will get old), but it's the best way to keep out moisture.

You could try a bottle or two of Heet, which helps dissolve small amounts of water in the gas so it can be slowly burned during use and eliminated.
https://www.goldeagle.com/tips-tools/symptoms-water-cars-gas-tank-and-how-fix-it/
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Old 05-07-2019, 09:51 AM
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Thanks UROParts - that’s exactly what I was doing - keeping about 1/4 tank. See my other post about using a full tank to protect components like the fuel pump. However, the past so many trips to the station, I filled it or went to 10 gallons.

I theorize the moisture simply took this long to build up and get too high - however, I don’t understand how the moisture [UPDATE : probably just ethanol!] wouldn’t collect in droplets yet still cause a stall - if that stuff is polar moisture, which it appears to be - the particles collect in it [UPDATE : consistent with ethanol!]

Perhaps simply filling up now (it’s drained w/o flushing) would get it going again.

Last edited by Bukowski; 05-08-2019 at 10:26 AM..
Old 05-07-2019, 11:13 AM
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The Heet article says you can leave the tank drained for a while so any remaining water can evaporate out. If you don't want to do that, it would make sense to add 5 gallons of fresh gas and at least a quarter-bottle of Heet to absorb any remaining water, or as much gas as you want as long as you follow the Heet's recommended ratio.

After you burn all the Heet-treated gas, consider using STA-BIL with a 95%-full tank in the future. (We have no affiliation with Gold Eagle products, but have heard good things.)
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Old 05-07-2019, 12:15 PM
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I was using sta-bil for a while and stopped- couldn’t be bothered.

However, the issue is not gas decomposing, but accumulating moisture.

Need to rethink my fuel strategy.
Old 05-07-2019, 12:54 PM
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Quote:
Originally Posted by Bukowski View Post
alright, had another road test. not good.

cold idling, seems ok. took a ride - warming up, went maybe 1/2 mile, stalls - a descending running stall (in gear) - not sure if this means anything. Almost stalled a couple times, had to press the accelerator to keep it going - had a jerking motion, a sort of spitting sound from the tail pipe (no backfires). Really hard to make observations of this. Clearly, the stalls are rapidly increasing in frequency, just from the past few miles.

Tested the fuel pump by simply jumping the DME (that standard technique). It runs OK by listening to the flow in the lines, and I stopped it within a minute or two. However, starting the engine and letting it idle - after it is already warm - results in a stall within a couple minutes. Not obvious why. Vacuum is still there - the reservoir line makes a hiss noise if the line is detached. Vacuum lines look and feel connected ok. Some odors observed are slight, and hard to specify - perhaps unrelated. No obvious smoke from the engine bay. No leaks still.

I still need to get my fuel pressure gauge. However - if the pressure is in fact low, or the delivery rate is low, it would only mean the pump is wearing out. (Thinking this out here ): There is a complete stall of the engine - and it's revival upon restart (this is sort of reliable). While driving the car, the performance seems OK, and then the engine stalls - but the car can remain in gear and slow to a stop without strange problems.

Question - what fuel pressure could explain an engine stall?
If your able to keep the engine running by increasing the throttle when it trys to stall it could be the TPS adjustment, also check the throttle cable is secured down between the bulkhead and throttle assembly and check there are no blockages at the airflow meter and check all linkage and butterfly's are working smoothly. Check the earth strap that's mounts to the enigne for deterioration should be replaced by now due to age. Make sure the idle control hoses are sound and not prone to collapse under pressure.

Old 05-07-2019, 02:51 PM
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