bc.gold 3,406 #1 Posted June 9, 2019 Neighbor gave me her old 92 Sierra, the truck sat for five years and the engine would only start by pouring a bit of fuel down the intake. She told me that the fuel pump had been replaced with a new one, turns out that "New" is new to truck. The new used fuel pump had quit so I replaced it, now the truck would on occasion start but not restart until it sat for an hour of so, research tells me that the ECU when the ignition is first turned on supply's power to the fuel pump for about 20 seconds to prime the system. My better half with decent hearing could hear the pump being activated so we knew now the ECU was doing its job and that that new fuel pump was wired correctly. Every local mechanic and some from the GM forum say to check the fuel relay, what they're missing here is that after the ECU primes the fuel system engine is supposed to start with oil pressure the pressure switch pass's power over to the fuel relay. In the event of a roll over oil pressure would be nil thus severing power to the fuel pump. The oil pressure switch can be bypassed for testing, now that this has been jumper-ed the relay is tested and its found to be working. This truck is not on my priority list so after fooling around with it over the past month, starting it for testing etc. the darn thing now starts every time at the touch of the key. Only thing I can think of is that the old ethanol fuel made the throttle body injectors stick in a closed position, I new that I had to drain the fuel to drop the tank and had used it over the winter in my Simplicity 9020 to blow snow, the old Onan didn't mind at all. The fresh fuel put in the truck after the new fuel pump was installed finally made its way through the system freeing up the injectors. I suppose fuel additives work but you have to get the engine running first and fuel injectors work a lot differently than carburetors and stuck injector will not pass the additives. Sometimes luck plays into your hand. Share this post Link to post Share on other sites
CCW 1,379 #2 Posted June 9, 2019 My wife's car's check engine light came on and the code indicated it might be a dirty injector. Put in a can of Sea Foam and the check engine light went away and the car ran perfectly. Now that you have it running add the Sea Foam. 1 2 Share this post Link to post Share on other sites
The Tuul Crib 7,339 #3 Posted June 9, 2019 Sea foam is good on some applications . These smaller engines mix at a smaller rate. I still strive for the no ethanol if you can find it. 1 Share this post Link to post Share on other sites
ztnoo 2,300 #4 Posted June 10, 2019 https://www.pure-gas.org/ 1 Share this post Link to post Share on other sites
