HELP_ 5th fuel pump

[[email protected]]

Hi guys, I LOVE suburbans, this is my 5th, but I have a problem that is stumping me.

1999 GMC Suburban 1500 4x4, Vortex 350, 248000.Automatic ( engine rebuilt 87000 miles ago)

LOCATION: top of a mountain in Colorado, no garage or cement to work on, drive 14 miles a day on rough road base.

PROBLEM: Installed AirTech ( yeah I know) 2 yrs. ago. ran well until 6 wks. ago. Died. replaced with Delphi, drove 2 weeks,DIED. Installed another, 2 weeks, DIED, Installed another, DIED after about 2 weeks, Installed ANOTHER, yep died. Getting ready to install another. ( yes I did cut a hole in my back deck to access pump)

SYMPTOMS: Historically will start immediately ( 3/4 cranks max), when going bad will take longer to start or not start at all. Mostly happens after sitting over night, once started (warm) seems to continue starting. No odor of gas. Mileage has stayed about the same. When driving ( 0 -80 mph) no noticeable problems ( stuttering, lack of power, missing) Tank looks excellent after inspection- have gone through over 200 gallons since this started, NEVER under a half tank of fuel.

Procedures completed: installed 5 NEW, under warranty Delphi's. Replaced fuel pump relay, replaced in line fuel filter ( on frame), replaced pig tail from pump to wiring harness ( 4 times), replaced distributor cap. ( all within last 2 months)

Checked and cleaned ground from pump to frame.

Had another fellow check voltage at pigtail. ( said it looked correct)

 

Any ideas? I really don't want to take off the manifold to replace the fuel pump pressure regulator.

 

Please speak English when leaving replies, I'm not great with voltage meters.

 

 

[sahls01gmc]

Richard, it sounds like you have an electrical problem that is shorting out your fuel pumps. 1 or 2 could be bad, but 5 sounds like an issue that is NOT the fuel pump. Can you verify that you have 12V to the fuel pump when they key is "ON"? And can you verify there is 0V when the key is in "ACC" or "OFF"?

 

That's 1 idea that you did not describe that might be worth a shot.

[Black02Silverado]

I agree, sounds like the pump is getting fried by getting the incorrect voltage. What is the fuel pressure at the rail on the engine?

[barry G]

if the harness all checks out, check grounds that are nearby.

 

I killed one to an electric trailer brake gadget, and bad circuit boards on the tail lamps.

 

that ground is on the left rail like the fuel pump...way in the back by bumper.

 

these trucks, especially suburban, they did not implement diode guidance due to the size of everything...the grounds can come back and bite each other anyway.

 

Tungsten bulbs are out too..that is a HUGE helper to go over to LED.

if to do my chores over.. I'd start with the ebay tail lamps all prebuilt. I ended up installing those last on my own truck.

 

rid the trailer brake gadget if you have one. Ground included, after removing power sources.

 

88-99.

 

Some other odds and ends...

full swap, sending unit, gasket, everything, all at once. Problem may be in the fuel gauge unit.

a rubber in the return lines may be infecting. If it responds to better warm runtime, it may be a goopy problem, not an oxide.

I never stick to one gas station as well.. that helps it stay dynamical.

 

it is good to avoid "new old stock", as there is subtle changes after 2008.

I went with carter.

[[email protected]]

Wow, thanks for all the replies. I will check them in the next day and reply back,

[[email protected]]

I agree, sounds like the pump is getting fried by getting the incorrect voltage. What is the fuel pressure at the rail on the engine?

According to the mech. who did the distributor it is 55 / 60

[[email protected]]

if the harness all checks out, check grounds that are nearby.

 

I killed one to an electric trailer brake gadget, and bad circuit boards on the tail lamps.

 

that ground is on the left rail like the fuel pump...way in the back by bumper.

 

these trucks, especially suburban, they did not implement diode guidance due to the size of everything...the grounds can come back and bite each other anyway.

 

Tungsten bulbs are out too..that is a HUGE helper to go over to LED.

if to do my chores over.. I'd start with the ebay tail lamps all prebuilt. I ended up installing those last on my own truck.

 

rid the trailer brake gadget if you have one. Ground included, after removing power sources.

 

88-99.

 

Some other odds and ends...

full swap, sending unit, gasket, everything, all at once. Problem may be in the fuel gauge unit.

a rubber in the return lines may be infecting. If it responds to better warm runtime, it may be a goopy problem, not an oxide.

I never stick to one gas station as well.. that helps it stay dynamical.

 

it is good to avoid "new old stock", as there is subtle changes after 2008.

I went with carter.

I will check for other grounds ( 6 in. snow today ) did a full swap when I did the relay change. I always buy from different stations also, Do you think a "line cleaner" would help with "goopy" lines?

[Black02Silverado]

According to the mech. who did the distributor it is 55 / 60

That checks out.

[Duelin]

According to the mech. who did the distributor it is 55 / 60

55/60 is within normal range. What are the pressures when you condemned the pumps? Those engines have the CPI injection system. And with the mileage that you have on the vehicle if it hasn't been changed it is coming to the end of its useful life. Or may be even past it. One of the symptoms is hard starting in the mornings. That is cause by the regulator or injectors leaking overnight and causing a flood condition. If you decide to or have to replace the system go with the MPFI conversion.

[muddkatt]

If you are getting 55-60 psi, then the pump is good. Have you checked the inline fuel filter that is in the frame rail?

[[email protected]]

If you are getting 55-60 psi, then the pump is good. Have you checked the inline fuel filter that is in the frame rail?

Fuel filter was changed on 2nd pump

[oldmann]

If the tank is not venting correctly it would overwork the pump and burn out quicker. Does this truck have an evaporative system that is not working?

[[email protected]]

Hi folks, Thanks for all the good suggestions but lets go in another direction. I've had the same pump in now for ALMOST 4 weeks (WOW) but about 2 weeks ago I thought it was time for another one......BUT after turning the key on and off 3-5 times she starts up now???? It suggests that I am losing my prime on the fuel system. The longer it sits the more it takes to start up. Once started it starts each time every time UNTIL I let it sit overnight or longer.

 

Symptoms

With a new pump starts great and normal for about 2 weeks

After 2 weeks is when problems start.

Today it took the longest to start ( 8 attempts of cranking for 4-5 secs.) after sitting 2 nights.

 

1st crank- nothing

2nd crank- sputter

3rd crank-sputter

if lucky 4th crank starts normally

 

If i just turn the key on to prime system it doesn't make a difference

 

**still caring another fuel pump in the truck...geez

 

Any thoughts