Car struggles & dies w/ fuel pump whine

[rockola1454]

Hi! Hoping to get some expert opinions on a tricky problem :)

When I bought my car in 2008 the fuel tank had been cleaned by the previous owner, and I had a local shop replace fuel lines & fuel filter. I keep the car garaged. Engine was replaced in 2019 with a new PRV Stage2 at DMCH (the boost in horsepower is nice!)
Around 2020 I had problems w/ the control pressure regulator, and a local mechanic sent it to DMCH for rebuild, and no problems with that since. Accumulator was replaced around 2023 for a warm start issue, that has been fine since as well.

In 2024 it developed a painful issue: once it warms up, usually after an hour of driving, the car sputters to a stop, and the fuel pump makes a loud whine. If you wait 10 minutes, it will start & drive 3 minutes before it dies again. After it cools down for several hours it behaves normally again. I typically go for long drives, so depending where it dies, can be tow truck time.
I had a local mechanic diagnose, and he replaced the fuel pump with a new one from DMCH & ensured everything in the tank was setup right and no hoses were kinked etc. and a new fuel filter. The fuel tank still looked clean inside. The engine dying problem went away after his work.
In 2025 I drove the car about 1K miles, several 3+ hour long drives, and it was perfect, not a single stall.

Thursday the problem has returned, exactly the same as before. I question that the pump or filter were actually the real issue in 2024 now. If it matters, the odometer reads 59k miles, but the new engine doesn't have many miles on it, maybe 10k-ish.
Now the question is, what in the engine compartment would cause the fuel pump to whine up front and engine to sputter to a stop randomly? What all should I have a mechanic check/replace to be sure the problem is fixed, and fixed for good so I don't keep getting stranded?
Any ideas much appreciated!

[WHO1DMC]

Well typically if the fuel pump has a high pitch whine and the engine is stalling or seems like it's loosing power, your pump is dying. I know you say it's fairly new but still could be going bad. I had a new pump last like 5 years or so.

Edit.
The replacement pump for the DMCH unit is the Herko Fuel Pump K9178. They cost like $30 or so from Amazon.



Dave B.

[Bitsyncmaster]

Did you replace the pump with the new all in one type (fuel pump and sender) or the NOS style using the NOS boots?

[dn010]

By indicating "no hoses were kinked" in the tank, I'm assuming you're running the original style setup / pump still. I have found that they don't last too long running regular 87 pump gas with ethanol. Especially if the car is not driven every day. Fuel with ethanol, sitting in the tank for a period of time, would not be good even for the "modern" pump.

[Timeless]

By indicating "no hoses were kinked" in the tank, I'm assuming you're running the original style setup / pump still. I have found that they don't last too long running regular 87 pump gas with ethanol. Especially if the car is not driven every day. Fuel with ethanol, sitting in the tank for a period of time, would not be good even for the "modern" pump.
When I was still on the original style pump and K-Jet I would only use ethanol free fuel. Had no issues.

[dn010]

Ethanol free is the only gas I will put in now. I found out the hard way what E10-E15 does after sitting in the tank a few weeks and then being run through the system.

[Timeless]

Modern pump? I'm running modern pump but don't let fuel sit more than 10-12 days - it gets used.

[David T]

If the pump is noisy it could indicate a bad pump. To diagnose it properly you would put a pressure gauge on the fuel system and monitor the fuel pressure to see if the motor is stopping due to lack of fuel. Lack of fuel can be caused by a bad fuel pump or an electrical problem shutting the fuel pump off (a bad relay, a bad inertia switch, a bad connection, etc).

If the motor is NOT stopping due to a lack of fuel you might want to check for spark. A not uncommon problem that could cause the motor to stop after a while is a bad impulse coil inside the distributor. Also check the connections on the white ballast resistor on the firewall. They can rust causing a lack of spark.

[rockola1454]

The new fuel pump is the original style, just the pump inside a black rubber boot (without sender). Looks like I got the pump & some other parts from DMCH in June 2024:

110085A ORIGINAL STYLE FUEL PUMP (AFTERMARKET)
101643A FUEL PUMP SCREEN FILTER (AFTERMARKET)
106287 FUEL PICK UP HOSE
106318 FUEL PICKUP HOSE GROMMET

The new rubber boot assembly I think I got from DeLorean Go.

I was looking around for a receipt for a fuel filter around that time, but I can't find evidence that I ordered one. I jacked the car up and can see the one on there behind the rear drivers side wheel looks kinda shiny, but there is a fair amount of rust on the fitting screwed into the bottom of it. I was sure the fuel filter was replaced along with the pump in 2024, but now I'm questioning whether that actually happened...
Could a fuel filter cause this problem, running an hour then suddenly obstructing fuel flow? I know it isn't the original filter but it is possible it has been on the car more years than I thought...

[dn010]

Anything big enough to stop up a 2-4 or so year old fuel filter would have to make it through the screen on the intake hose in the tank and then the pump. Very unlikely. Those pumps don't like it even if the smallest debris is trying to get through.

I'm not there to diagnose everything but I'd start with the pump as being the culprit. The newer 909 pumps just do not last. I used to buy two of them at a time just so I would not be left stranded (https://www.ebay.com/itm/225619679693). You can pull it and test it when it's acting up or put a pressure gauge on as David suggested.

Gone are the days of fishing around in the tank for the inlet hose and hoping it isn't collapsed once installed. I now run modern pump, for a '02 Tahoe.

[rockola1454]

Thank you everyone for the replies!

> Anything big enough to stop up a 2-4 or so year old fuel filter would have to make it through the screen on the intake hose in the tank and then the pump. Very unlikely.

Ohh, that is a very good point!


> Lack of fuel can be caused by a bad fuel pump or an electrical problem shutting the fuel pump off

Since I hear a loud whine when it acts up (same as the old pump did in 2024), I would guess the pump is powered, but for whatever reason unable to move gasoline, thus the noise.


> I would say the pump is the problem.
> I'd start with the pump as being the culprit.

Interesting, I guess it's time for another pump :)

Is there anything after the fuel filer that once heated up could cause a blockage? Since the pump is only a year old and I never encountered this behavior in the 16 years prior to 2024, I am just wondering if something could be causing the fuel pump to whine because the fuel has nowhere to go? ...a failing fuel distributor wouldn't do that, would it? I don't remember mine ever having been serviced.


> If the motor is NOT stopping due to a lack of fuel you might want to check for spark.
> A not uncommon problem that could cause the motor to stop after a while is a bad impulse coil inside the distributor.

Hmm, interesting... maybe that's what's going on? The engine sort of sputters to a stop over 20-30 seconds rather than dying all at once, does that align with a bad impulse coil? I suppose a hot pump could whine if the engine stalls.
The trick is making it happen, the car has to be driving for about an hour :D But I could check spark next time.

> Also check the connections on the white ballast resistor on the firewall. They can rust causing a lack of spark.

Those are good, I've recently checked. I have a thin layer of dielectric grease on the ballast resistor terminals & the plugs are all tight.

[cis6409]

+1 on the pump. If its making that whining noise its usually on the way out. The cheap aftermarket pumps are that , there not made like they used to be . The cheap ones can last 5 mins or 5 years very hit and miss. Sourcing a reputable good gactory style pump is gettong very hard these days to avoid the china ones.
Try the 80 s porsche and mercedes supplied ones as they used k jet aswell from the sl500 or the porsche 924 for example, but they can get pricey so you maybe worth converting to the modern combo pump set up.

If you do get a factory style pump preferably one thats rated for 6 bar or higher if possible.

The only thing else that kills the pump prematurely besides debris is overheating. Make sure the mini 2 pin harness to pump loom is fresh and clean. If they are bad the pump isnt getting near the 12v supply it needs, the low voltage shortens the pump life very quickly.

Maybe get the cheap 30 dollar pump listed above as a back up

Also record a video of the whine,if you want to confirm?

Shane

[Bitsyncmaster]

The original pumps did whine when the fuel in the tank gets hot. I think most of the heating in the tank is due to the returned fuel from the FD and FV. The fuel heats up in the engine bay.

Before the new pumps showed up I had built a fuel cooler on the return fuel line and that did stop any pump whine. But I do think your better off just going with the new type pump.

[rockola1454]

I forgot to ask, what is the best fuel pump I can get as a replacement? I assume I should get the modern style with combined sending unit, is there a common model number?
Thanks!

[Timeless]

I forgot to ask, what is the best fuel pump I can get as a replacement? I assume I should get the modern style with combined sending unit, is there a common model number?
Thanks!
https://store.classicdmc.com/107000-fuel-pump-sender-module-six-month-warranty-from-date-of-sale-tank-must-be-completely-clean-prior-to-installation-evidence-of-fuel-system-contamination-will-void-warranty.html

If DMC stock does not return soon this is an alternative - an you'll need a V-band clamp similar to this: https://store.classicdmc.com/107388-retaining-clamp-for-107000.html

https://www.amazon.com/ACDelco-MU1777-Original-Equipment-Assembly/dp/B0049BMHZC/ref=sr_1_1?crid=1IPTAHHUX7NK6&dib=eyJ2IjoiMSJ9.oa7Gm5ASc8H1mcILmBp1OrIAjaK6hUSXe zAc61xchBI.9WQU7TTKdZ3K_Waj0JmCmj2q1R3gkpWHayAbIxt JQ8w&dib_tag=se&keywords=mu1777&qid=1774784954&sprefix=mu1777%2Caps%2C135&sr=8-1

[Helirich]

I?m watching this thread for updates. My car started stalling a few weeks ago when the AC was on and suddenly letting off the throttle. I put a bottle Lucas injection cleaner in a nearly empty tank. I drove it for maybe 20 miles with that high ratio mixture. Than I filled up and took it on a long trip to Mississippi. It has not stalled since. its possible the long trip got the system working good. I did have to run some ethanol on the trip, but I got it filled with non ethanol since.

One note, my pump was not whining.

[dn010]

Everything you will need, and exactly what I am using:

Pump: MPA27003 (O-Reilly) https://www.oreillyauto.com/detail/c/masterpro-fuel-pumps/masterpro-fuel-pump-module-assembly/fpm0/mpa27003?q=MPA27003

Clamp: 35805 Walker Exhaust Clamp (Amazon) https://www.amazon.com/Walker-35805-V-Band-Hardware-Clamp/dp/B0015KUD4C

Fitting #1 (you only need 1 but I got the 2 pack) https://www.amazon.com/Quick-Connector-Female-Straight-Tubing/dp/B07K6P3FC2

Fitting #2 (you only need 1 but I got the 2 pack) https://www.amazon.com/Quick-Connector-Female-Straight-Tubing/dp/B07MH258P5

Pump comes with a pigtail so you don't need to worry about finding one, and you can keep the stock sending unit installed in the tank for the gauge instead of worrying about adapting the modern one to the car, unless you really want to. Just leave the float arm off the new pump upon install. Get some new 5/16" EFI rated fuel hose and get rid of the original plastic lines.

[dn010]

Forgot to include this, you'll need one of these also:

In-line check valve (amazon) https://www.amazon.com/EVIL-ENERGY-Return-Petrol-Aluminium/dp/B08JJ128LN