Signs of a Dying Fuel Pump

[lazabby]

What are the signs of a dying fuel pump?

[DMCMW Dave]

What are the signs of a dying fuel pump?

Car stops running.

They don't often give much warning. Sometimes they will get noisy, but quite often they get noisy - and stay that way for years.

[DeLorean03]

Back in the day (2003-2005), here were my symptoms:

1. They get noisy - VERY noisy especially in hot weather. You'll hear a LOT of humming from the pump. It will be VERY noticeable. And it was NOT the humming of my two rubber fuel lines.

2. For my car specifically, you could hear the pump prime right before turning the key to start the motor. I noticed my fuel pump would sometimes NOT prime. This could have been strictly coincidental as my current pump from John does this. I am planning on installing the new pump/sender combo in January, so I'll be able to vouch better for this soon with the new setup.

3. You could start to experience a lack of or loss of power. Prime example, I would be driving along when all of a sudden I would lose 5-10mph on the interstate - almost as if the car was about to die - it would be right on the verge of dying but the indicator lights (oil and battery) would not come on. The car was RIGHT on the verge of those lights coming on but the car hung on. Turned out my pump filter came off and my pump was sucking up debris. Thank God, the pump hung on.

3a. Same as #3 but I would be going 10-15 mph in a parking lot and the car WOULD actually die. Sometimes the car would start right back up, other times I had to crank the motor a couple times before the engine caught and stayed running under its own power.

These are some of the symptoms I have experienced and dealt with in the past.

[WelmoedJ]

Back in the day (2003-2005), here were my symptoms:

1. They get noisy - VERY noisy especially in hot weather. You'll hear a LOT of humming from the pump. It will be VERY noticeable. And it was NOT the humming of my two rubber fuel lines.

2. For my car specifically, you could hear the pump prime right before turning the key to start the motor. I noticed my fuel pump would sometimes NOT prime. This could have been strictly coincidental as my current pump from John does this. I am planning on installing the new pump/sender combo in January, so I'll be able to vouch better for this soon with the new setup.

3. You could start to experience a lack of or loss of power. Prime example, I would be driving along when all of a sudden I would lose 5-10mph on the interstate - almost as if the car was about to die - it would be right on the verge of dying but the indicator lights (oil and battery) would not come on. The car was RIGHT on the verge of those lights coming on but the car hung on. Turned out my pump filter came off and my pump was sucking up debris. Thank God, the pump hung on.

3a. Same as #3 but I would be going 10-15 mph in a parking lot and the car WOULD actually die. Sometimes the car would start right back up, other times I had to crank the motor a couple times before the engine caught and stayed running under its own power.

These are some of the symptoms I have experienced and dealt with in the past.

+

My car lost speed a couple of times while on the highway (outgoing journey and on the way back home).
I couldn't get her to regain the speed I had before that happened.
I kept her going and tried to accelerate a couple of times without success.
Then suddenly she got over it and regained speed as before.
I could make it home though.

Fuel screen was still in place and screen and tank were clean, but the pump was on it's way out.
Replacement solved the pump issue.

[Bitsyncmaster]

As Dave said....Not often you get any warning. There are lots of things that can fail and make you think it's the pump. The pickup hose, RPM relay, inertia switch, bad connector (near fuel pump).

I had John's power pump and it's twisting when starting (mounted in foam to the boot) caused the pickup hose to tear.

[Delorean Industries]

I know it is a lot of work. Just like how I advocate checking the VOD once a year. I do these things on my own cars because I know it is for the best. Pump life also depends on its surrounding conditions. Pulling the pump cover and checking the boot is important. Pulling the pump out and checking the tank component condition is as well. You would be surprised how quickly with modern additives that the pump components degrade. These are all things that determine pump life and reliability.

[lazabby]

Reasin I ask is that I will get an occasional 200-300 drop in RPM when at a stop with car in Drive. The RPMs will be steady and then a sudden drop and then back up. Yesterday the car actually died twice on me while I was at a light. It started right back up with no problems. I wanted to know if it's possible that this might be a sign that the fuel pump is on its way out. Today I'll be checking the voltage and fuel pressure. I have EFI and I have a fuel pressure gauge. I'll also go over electrical connections although I cleaned up quite a few of them three or so months ago in fuse box and engine.

[DMC5180]

Do you have a Throttle Position Sensor?

[lazabby]

Do you have a Throttle Position Sensor?

No I don't.

[DMC5180]

Hmm, I always thought EFI needed that component. So much for that idea.

[kenny]

Reasin I ask is that I will get an occasional 200-300 drop in RPM when at a stop with car in Drive. The RPMs will be steady and then a sudden drop and then back up. Yesterday the car actually died twice on me while I was at a light. It started right back up with no problems. I wanted to know if it's possible that this might be a sign that the fuel pump is on its way out. Today I'll be checking the voltage and fuel pressure. I have EFI and I have a fuel pressure gauge. I'll also go over electrical connections although I cleaned up quite a few of them three or so months ago in fuse box and engine.

Very interesting, I have a manual with k-jet and the same thing has been happening my car last 2 times I have had it out. I haven't had time to look at it yet. All the dash needles go crazy for a split second for me. I had planned on cleaning all the grounds as a first port of call and next checking the rpm relay.

[Bitsyncmaster]

Very interesting, I have a manual with k-jet and the same thing has been happening my car last 2 times I have had it out. I haven't had time to look at it yet. All the dash needles go crazy for a split second for me. I had planned on cleaning all the grounds as a first port of call and next checking the rpm relay.

Sounds like the ground behind the rear shelf is your problem

[Patrick C]

Sounds like the ground behind the rear shelf is your problem
Or the ground on the top of the frame extension behind the driver front wheel.

[Spittybug]

Hmm, I always thought EFI needed that component. So much for that idea.

The TPS is only used for one of the two options for acceleration enhancement. Manifold vacuum change, while a bit less responsive than throttle position change, works fine.

Your question may have merit however.... there could be phantom "noise" of some sort being generated on the TPS input wire. In fact, I am running a code variant of megasquirt that includes a TPS signal smoother since without it the TPS signal gets random fluctuations that can cause unintended increases of fueling (normally only for acceleration) when least expected. It can give a feeling like a "miss" when cruising.

I don't have the log any more Shannon. Check your TPS and PW to see if they get goofey at the stall event. (can carbs log?)

[Bitsyncmaster]

Or the ground on the top of the frame extension behind the driver front wheel.

Since the pump current shares the instrument ground, that points to a ground fault after that common ground wire. That ground wire goes back to the bolt for the rear grounds.

[lazabby]

In the log the PW has an inverse relationship with the RPMs - it goes up when the RPMs dropped. Generally it tends to move i nthe same direction of the RPMs.

[kenny]

Sounds like the ground behind the rear shelf is your problem

Just did a check and the ground cable on the bulkhead in engine bay was a bit loose, need to take car for a spin to confirm that the problem has gone but looks like it.Thanks for the tip Dave, very much appreciated