Is it possible to have a bad electric fuel pump if the vehicle still runs?

Question

If it is possible to have a bad electric fuel pump and the vehicle still does run--what are some signs/symptoms that your fuel pump may be bad or is going bad.Thanks

--if it matters its for a 1987 GMC pickup with a 350 tbi.

There are some really good helpful answers here.Some even describing my trucks symptoms perfectly and others even giving me part numbers.It looks like most of you put alot of effort into your answers so i would be hard pressed to pick a best answer so i will let this go up for a vote.Thanks to all for your help.I'm gonna replace my fuel pump this week.Thanks again!!

Answer 1

Yes your pump can be bad, or going bad and the vehicle still operate. The only way to know for sure is to check the fuel pressure.

1. Remove air cleaner and plug THERMAC vacuum port on throttle body unit.

2. Remove fuel line between TBI unit and fuel filter. Use a suitable back-up wrench to hold flare nut on throttle body when removing line.

3. Install fuel pressure gauge J-29658 or equivalent, between throttle body and filter.

4. Check pressure reading with engine running. Fuel pressure should be between 9 and 13 psi.

5. De-pressurize fuel system, remove pressure gauge and reinstall fuel line.

6. Start engine and check for fuel leaks.

7. Remove plug from THERMAC vacuum port and install air cleaner. *** THIS PROCEDURE HAS BEEN UPDATED BY TSB # 90-6C-89, Dated 9/90 Some 1985-90 engines equipped with 2.5L, 2.8L, 4.3L, 5.0L, 5.7L or 7.4L may experience a condition where fuel delivery is interrupted to the engine causing a "no start condition". This condition may be caused by deterioration of the in-tank fuel pump coupler hose located between the fuel pump sending unit and the fuel pump. This condition may be repaired by replacing the original coupler hose with a new VITON coupler hose kit P/N 25028041. The kit consist of a new VITON hose and two clamps.

Answer 2

When it totally goes, the car will either die or fail to start. Often it goes with no warning.

If it's just getting worn down, then you may suffer a lack of sufficient fuel when you drive, so your vehicle will probably lose power while driving, may feel like it's going to (or actually will) stall, and you have trouble driving at regular speeds. Then it might magically be fine after that, or it may stay that way for a while.

Incidentally, if you run out of gas a lot, that puts a lot of wear and tear on the pumps, which aren't meant to run dry.

On an '87, it'd probably be worth it to replace it anyway - if it hasn't gone by now, it's going to go soon, unless you put on very few miles.

Answer 3

FUEL PUMP?

I can only tell you the problems I had on my '91 Chevy 2500 w/350 tbi.

Over a three month period, the truck developed less "top end" power. It would rev up to redline, but didn't have the same power as moderate throttle and moderate engine speeds.

It got to the point where it would crapout if I floored it trying to get on the freeway, but would still run fine in downtown traffic.
It would start right back up, but die as soon as I tried to merge back into the freeway traffic.

As it worsened, I could not get above 50 MPH, then, it finaly would not do more than idle.

I changed the fuel filter, and that helped briefly, and then finaly died completely.

The pump and fuel gage component in the tank is about $250.00

I had to change mine, and haven't had a problem since.
I take that back....I had to change the rotor and Dist. cap.

If you have to change the pump, the locking ring is kind of tricky to figure out how to remove it. It's got a center locking ring that turns. NOT the outer ring.

Answer 4

Yes, a fuel pump can be bad even though the truck still runs. The pressure could be too low.

Symptoms you may notice include long cranking time when starting, stalling when put into gear, and/or lack of power when accelerating.

Have a fuel pressure test performed.

Although I have only seen it a handful of times, if the pressure is low it could be caused by a restricted fuel filter. If your fuel filter is so plugged up that it reduces the fuel pressure then it is probably only a matter of time that the pump fails due to the stress of trying to pump through a plugged filter.

Another unlikely source of a fuel problem could be caused by poor power to the pump.

Answer 5

if the pump goes,then it wont start.listen for a humming noise,when you turn the key on.also run a test on the fuel pump off the fuel rail.it could be a dirty gas filter also.

Answer 6

the easiest way to tell is turn the key on and liston for the pump to hum it only does that for a second so listen good

Answer 7

your car wont start and it willl stop running! do not let your gas gauge get below 1/8 of a tank.

Answer 8

yes! listen to it , it will tell you by making noises. sometimes they will work ok on and off, so listen at different times.

Answer 9

It won’t start.

What are some other symptoms of what’s going on, maybe I can help you out.