I have an "88" Buick Riviera 3800. Ocassionally when I go to start it, it turns on but will not stay on. It shudders and turns off. I have a hunch it may be an electrical problem, but I'm not too sure. The following is additional info for anyone who can help me. I have a new battery, new alternator, car has a distributorless ignition system, the starter is fine also, has new plugs and cables. Oh, and I had to install an external fuel pump cause the other one stopped working so thats new too! I am baffled, can someone please help me. All suggestions are greatly appreciated. Thanks Diana

[color:"blue"]Do you know the fuel pressure? Did the car ever run right with the external pump? Did you remove the internal (to the fuel tank) fuel pump or are you trying to suck fuel through it?

The car starts on the ignition module and turns over control to the ECM at about 400 RPM. When it starts does it get past this point?

I know lots of questions, but these may lead to us to what we need to know.[/color]

If the original pump is in place I don't believe it will run unless the original pump is also operational. Most in tank pumps are the gerotor type and it should be virtualy impossible to suck through it. Check the actual fuel pressure, it should jump right to 42-44 psi as soon as the key is turned on.

I'm not to sure of the exact fuel pressure, but the car did run with the external fuel pump. I put in the external fuel pump cause the car was doing to same thing before, and we saw that there was no fuel pressure. So after we installed the new one it started right up. But afterward the car was never the same, now it won't stay on at all. We did not remove the internal pump. I have to ask my fiance how he installed the external fuel pump. And I'm not too sure about the rpm # at start up, but I'll find out and write back.

[color:"blue"]I'm thinking you need to fix the internal fuel pump, and remove the external pump. Whatever you do a pressure gage that attaches to the fuel rail would be helpful to make sure your repair affords enough fuel to properly operate the engine.

The internal pump may be OK with the sock filter internal to the tank collapsed and stopping fluid flow. These can easily be replaced, after dropping the tank of course.

If the pump is dead it needs to be removed, and it would be easier to replace than figure out how to place the pick up filter on the end of an extender tube at the bottom of the tank. [/color]

We replaced the internal fuel pump, and took off the external fuel pump. And the car started, Thank Alot Everyone

Yipee! <img src="http://www.aaca.org/ubbthreads/images/graemlins/laugh.gif" alt="" /> Thanks for letting us know how it came out.