Unable to get fuel pressure from gas tanks. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

twoodson · 09-21-2003, 06:36 PM

Hello guys, I live in Lancaster, TX. I have a 1987 SWB with a 350 tbi with dual tanks The other day I was on the way to take my 5 year old to football practice and suddenly the truck sputtered and went dead. My mechanic noticed that there was no fuel injector pressure and the 10 amp fuse for the ECM was blowed. Replaced the fuse, turned the key and the fuse popped again. We tried a heavier amp fuse and guess what it popped again. The engine turns over but will not start. We replaced the ECM and we now had injector pressure. We can hear the fuel pumps come on. We sprayed carb cleaner in the TBI and it started. We took apart the inside dual tank switch and we tested it and it was okay. Is this a selector valve problem. Do anyone know were I can locate a printed diagram of the wiring for the dual tank setup. Thanks for your help we will get back on the truck tomorrow..HELP!!!!!

79BIG10 · 09-21-2003, 08:45 PM

Welcome to the board

Sounds like you're right in thinking that it's the valve itself. Look at this thread here. Maybe this will help. http://67-72chevytrucks.com/vboard/s...threadid=69423

twoodson · 09-22-2003, 02:00 PM

Thanks 79big10, my mechanic was out sick today so hopefully we can get on this first thing in the morning. It just amazed us as to how this happened and shorted the ECM when the tank issue was running a different circuit. Anyway I will let you know how I came out.

twoodson · 09-27-2003, 12:49 PM

Finally got the 1987 swb on the road again. It was the Selector Valve that was causing the problem. Still not understanding why it caused the ECM to blow the ECM fuse. All the wires were okay. I am now able to switch between both tanks, however when I switched to the left tank (which had about 1/4 tank of gas in it) the fuel gauge registered way past the F mark on the gauge. I switched back to the right tank and it is reading correctly. My mechanic suggested not to use the left tank because it seems that something maybe grounding out within the left tank and this may have caused the whole problem from the beginning. We are going to drop the tank and see what's going on. I am almost there. Thanks 79big10 for all your help!!!! 73-87

79BIG10 · 09-28-2003, 12:47 AM

Your welcome. Glad to see everything working out. Your mechanic is right in that the ground is the problem on the left tank. This is a very recurring problem on our trucks. Just look for the ground wire and reattach it and making sure the ground is good and secure.

09-21-2003, 06:36 PM	#1
twoodson Registered User Join Date: Jul 2003 Location: Lancaster, TX Posts: 291	Unable to get fuel pressure from gas tanks. Hello guys, I live in Lancaster, TX. I have a 1987 SWB with a 350 tbi with dual tanks The other day I was on the way to take my 5 year old to football practice and suddenly the truck sputtered and went dead. My mechanic noticed that there was no fuel injector pressure and the 10 amp fuse for the ECM was blowed. Replaced the fuse, turned the key and the fuse popped again. We tried a heavier amp fuse and guess what it popped again. The engine turns over but will not start. We replaced the ECM and we now had injector pressure. We can hear the fuel pumps come on. We sprayed carb cleaner in the TBI and it started. We took apart the inside dual tank switch and we tested it and it was okay. Is this a selector valve problem. Do anyone know were I can locate a printed diagram of the wiring for the dual tank setup. Thanks for your help we will get back on the truck tomorrow..HELP!!!!!

09-21-2003, 08:45 PM	#2
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,775	Welcome to the board Sounds like you're right in thinking that it's the valve itself. Look at this thread here. Maybe this will help. http://67-72chevytrucks.com/vboard/s...threadid=69423 __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson

09-27-2003, 12:49 PM	#4
twoodson Registered User Join Date: Jul 2003 Location: Lancaster, TX Posts: 291	On the road again!!! Finally got the 1987 swb on the road again. It was the Selector Valve that was causing the problem. Still not understanding why it caused the ECM to blow the ECM fuse. All the wires were okay. I am now able to switch between both tanks, however when I switched to the left tank (which had about 1/4 tank of gas in it) the fuel gauge registered way past the F mark on the gauge. I switched back to the right tank and it is reading correctly. My mechanic suggested not to use the left tank because it seems that something maybe grounding out within the left tank and this may have caused the whole problem from the beginning. We are going to drop the tank and see what's going on. I am almost there. Thanks 79big10 for all your help!!!! 73-87

09-28-2003, 12:47 AM	#5
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,775	Your welcome. Glad to see everything working out. Your mechanic is right in that the ground is the problem on the left tank. This is a very recurring problem on our trucks. Just look for the ground wire and reattach it and making sure the ground is good and secure. __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson

09-22-2003, 02:00 PM	#3
twoodson Registered User Join Date: Jul 2003 Location: Lancaster, TX Posts: 291	Thanks 79big10, my mechanic was out sick today so hopefully we can get on this first thing in the morning. It just amazed us as to how this happened and shorted the ECM when the tank issue was running a different circuit. Anyway I will let you know how I came out.



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