fuel pump problems?

[do92sc400]

I am brand new to this site, and so far I have really enjoyed the info. Know I hope someone can help me with my problem. I recenlty purchased a 92 sc400. Until recently I did not have any problems with it. Now, when I start the car sometimes it starts and sometimes it only runs for about three seconds then it dies. If I wait about twenty minutes (sometimes more), then it will run. After I arrive to where I was going the car will not start. (then here we go again).
I have already changed the fuel filter with no success. I work for an auto parts store so I know how much a new pump will cost. Can someone please give some advice on how I can trouble shoot the problem. Hopefully I don't need to buy a new pump.

 

[SCV8]

You need to first verify that the fuel pressure is adequate, I would probably try and remove the cold start injector and use that supply line for attaching a pressure guage.
I have not had to check for pressure on these cars, maybe someone else has a better way?

 

[do92sc400]

That's the strange thing. When the car does decide to start, it runs without ever shuttingoff like if fuel pressure is normal, except that the idle is a little rough. It seems like something is making the pump turn off after the ignition is turn on.

 

[Lextreme II]

It might be an electrical short somewhere. Check the fuse box under the hood. It might be the relay or the relay contacts are loose.

 

[sideshow]

ive had a prob before on customers car where it stalled when the car fit about 6kmph

found relays to have bad contact and also around battery area had corroded so might have had bad earth

 

[cribbj]

You could be losing the crank speed (Ne), Cam sync (G1/G2) or ignition event (IGf)

The intermittent loss of any of these would produce the symptoms you have. I'd start pushing & pulling on the wires and connectors for these signals while the engine is running, and see if you can get it to die.

 

[do92sc400]

I do appreciate all the advice guys. Found out that the problem was caused by a faulty fuel pump control (fuel pump ecu). Turns out that all I had to do was splice the red/black wire with the green wire of the control (ecu) harness, which made a full 12volt by pass to operate the pump. Only thing is that now the fuel pump now works at full capacity rather than at cruise mode. Car does run great but can already tell that this should only be a temporary fix until I can find a new ecu for the pump. Thanks again for your help

 

[sideshow]

i do have a fuel pump ecu of a soarer or an aristo lying aorund here somewhere
i might be able to sell it