I have a 90 GMC 35000 with a 454 TBI motor. It died today and felt as it was running out of gas. It has duel tanks, both have fuel in them. I switched to the second tank, the truck would not start and all of my gauges pegged out. I switched the tank back to the first, gauges went back to normal and the engine will start but only runs for about 20 seconds at a time. I'm thinking the electric fuel valve may have gone south, but wanted some advice before replacing the valve.

Thanks, John K

 

It may be that your fuel pump is going. I had a similar issue with my '90 350, and it would start and run for about 20-30 secs, then die out. I would be pumping the gas like crazy to try to keep it going, but it finally gave out. When I went to test the pump, it would work sometimes, but wasn't pumping what it should be.

 

I'm thinking fuel pump also. Question is, with duel tanks, is there a pump in each tank or just one pump that pulls from both ? I found the ground wire from the battery to the chassis had come loose. Putting it back on solved the gauge problem, but it will still not run on one tank and only 15 to 20 seconds on the second tank. If it has two pumps, seems strange they would both go south at the same time. I'll have to check the fuel pump relay. It's about 108 degrees out now, so I'm not too motivated to figure it out till it cools a little this evening.

 

if its 108 check to see if its vapor locked ....my jeep does this quite regularly now when it gets hot....I am not sure either on the dual fuel pump thing, but I think it has a filter on the side of the frame, maybe its plugged as well.......