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What Happens When Fuel Pump Fails While Driving?

henson

By henson,
in Engines & Forced Induction

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henson Collaborator

henson

Posted
Posted

Hi all,

The other day I was driving (not on boost, just cruising) and as I came out of a set of lights my car choked (jolted quickly). I continued to drive and then it came back.. I was like it wasn't getting fuel as it was on then off and I couldn't use any acceleration (but I could be very wrong).. I've been lucky enough to not have any previous fuel issues, and in this case I'm not sure if that is the problem... I nursed it as far as I could until I came to a stop and that was the end of it, wouldn't start after that.

The reason I suspect fuel is after a big upgrade (turbo, injectors, ecu etc) the only thing I hadn't replaced was the fuel pump which was already a Walbro 500hp pump..

If anyone has had a similar problem or could tell me what happens when a fuel pump goes (while driving) I'd much a appreciate it.

Daniel

GTSBoy Grand Master

GTSBoy

Posted
Posted

Pretty much what you said. Depends on if it dies 100% all at once or if it has a few fits and jerks, which is what yours sounds like it might have done.

Could also be AFM given those symptoms (if you're still using one) or conceivably the CAS or igniter.

G4orce Veteran

G4orce

Posted
Posted (edited)

i had exactly the same problem and it happend all of a sudden while driving, the car had absolutely no guts and was choking then it will drive normal for a little bit.

check that the plus wire isnt earthing. the dude i brought the car off changed the fuel pump to a walbro and he used electric tape instead of heat shrink to cover up the solder welds and it was earthing.

i took the pump out re did the wiring and it was all good after that.

Such a small problem i had to pay $150 to get the car towed home

I would definately check out the wiring as you got an aftermarket pump.

Edited by G4orce
henson Collaborator

henson

Posted
  • Author
Posted

@GTSBoy yeah true, that's exactly what happened, I don't use an AFM as its done off map sensor/ecu..

The car still primes BUT its not the usual sound, sounds suss to me anyway..

Does Checking the filter and wiring require me to take the pump out completely?

When this happened, I had the HICAS light flashing as well (not sure if that has anything to do with it tho)...

@G4orce, did your car end up stopping and not being able to start after until you fixed the problem? Seems I've got exact or similar problem and I don't wanna get it towed if it's as easy as you said but just fixing the wiring..

Thanks for the input!

G4orce Veteran

G4orce

Posted
Posted (edited)

@GTSBoy yeah true, that's exactly what happened, I don't use an AFM as its done off map sensor/ecu..

The car still primes BUT its not the usual sound, sounds suss to me anyway..

Does Checking the filter and wiring require me to take the pump out completely?

When this happened, I had the HICAS light flashing as well (not sure if that has anything to do with it tho)...

@G4orce, did your car end up stopping and not being able to start after until you fixed the problem? Seems I've got exact or similar problem and I don't wanna get it towed if it's as easy as you said but just fixing the wiring..

Thanks for the input!

yea i drove around for about 5 km then got stuck on the road so i had to get it towed home . i didnt want to leave my car on the side of the road overnight. My cars pump primed also andyes you will need to take the pump out to check both filter and wiring.

Edited by G4orce
paulr33 Grand Master

paulr33

Posted
Posted

yeah i guess to be clear there are two scenario's here

one is the pump fails completely and stops pumping fuel

in this case the engine would basically stall or cease acceleration and slowly come to a halt

the other scenario is the pump cannot keep up the required LP/H rate for the engine and the fuel flow rate, and pressure drop off or "lean"

this coupled with the engine being on full load, make stuff go bang. the engine slowly leans itself out, the exhaust temps would climb, the AF/Rs would continue to lean out

and eventually the engine would either blow valves, melt the exhaust, melt pistons etc and fail

this would have to occur over a period of sustained MAX load and it wouldnt just happening cruising along

ie it would have to be a good 1 to 2 minutes run at full song and a pump that cant keep up to cause this type of failure (i expect)

the last one is even more "variable" because is the pump failing, or are you expecting too much flow from it ?

Hanaldo Grand Master

Hanaldo

Posted
Posted

Depending on the power level you could probably detonate and melt an engine to death with a leaning out pump in less than 20sec, which is really only one decent run to top speed.

Trying to recall the last time I was on the fast-button for 20 seconds... And it's not coming to me lol. Sounds like fun though, SAU trip to the Autobahn? :P

G4orce Veteran

G4orce

Posted
Posted (edited)

its a walbro. due to happen sooner or later.

whats wrong with Walbro, as long as its genuine Walbro with metal gearing there a good pump.

iv been running walbro for the last 5 years on all my cars not 1 problem.i know many people who use them and there all happy with the pump.

i like Walbro as its not as noisey as a Bosch

Edited by G4orce
D.I.Y. Mik Veteran

D.I.Y. Mik

Posted
Posted

Depending on the power level you could probably detonate and melt an engine to death with a leaning out pump in less than 20sec, which is really only one decent run to top speed.

Lucky we have crank oil and a cooling system.

My old two stroke bike leaned out on one of the two cylinders; about 1.5 seconds later, BANG! rattle rattle....

Molten crank bearing metal blobs stuck to the spark plug. Dead bike. Old bike. No parts available.

20 seconds is an eternity to realize theres a problem and do something about it.

Dont we have gauges for this kind of thing?

If you had an air fuel gauge youd know.

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