fuel pump????

I searched the forum for a idea of what was going on here but found nothing so, heres the problem.

I have an 88 s10 blazer that I just got done replacing the 2.8 to a 3.4 got it all hooked up and now there is no crank when you turn the key. So I jumped the starter and it will turn over just fine. pulled the inigtion swicth like someone said in a post earlier and tore in to it. found the sol. tab had some buildup on it.cleaned it up, and reinstalled it. now it will crank over but no fuel pump, not a sound, so I removed the pump and found that the ground wire was in bad shape , put a new ground wire on it, checked the pump while I had it out with a battery and some leads, came on did not run it just for a sec. or two. Reinstalled the pump connected the new ground to a freshly wire brushed area. Tryed it and no pump? So I went and got a new relay and still nothing. I put a test light on the plug coming to the pump and it shows there is voltage there but if you plug it back to the pump no go...Tested the wire between the plug and the pump no voltage, unpluged the plug and have voltage again?

Sorry for the long post but I thought if I told you all what I had allready done it would help you all in helping me figure this out.

One more thing I do not have a check engine light when I turn on the key. and I dont understand the fuel prime signal either.

Any help please....

If you bench tested the pump and it ran and it doesn't run after you in stall it. You need to check the exact voltage that is going into the pump. Also double check your ground wire. If the voltage is to low. The pump will not operate. If that’s the case. Run a hot led wire from your car battery and while the pump is still in place in the tank. Connect it to the Positive led and see if the pump operates. If so, then I'd go and look at your ignition switch again. There is a possibility that the contact for your fuel pump is either still a little dirty or not making contact.

Ok replaced the ing. switch and still had no fuel pump, took my volt meter back to the pump and unpluged the connector and had 9.5 volts, with the key in the on postion , so I put the plug back together and checked and had no voltage at all. so I left the meter hooked up and unpluged the connector and the voltage came back?

Any ideas

no ideas

You need 12 volts back there. If your not getting 12 volts with the key on, you have to trace the wire back to the front of the truck. Also, check your ground for the pump too.

does anyone know where the next place back from the pump is that I can check the voltage?

Also can I run a power wire straight is the pump from the fuse box with a swicth that I can turn on as I start the engine?

Also something just came to me.....do you have a fully charged battery? If you have anything under 10 volts, that *could* hinder the operation of the ECM. You need over 10 volts. I would first be looking at this first.



If that checks out, then I read on.

I would start by pulling the harness from the back, you checked at the connector, but did you try probing it before the connector at the back? How about at the relay, are you getting 12 volts at the relay, both before and after the relay? If your getting 12 volts at the realy, then the problem lies somwhere between the relay and the wiring to the pump. If your not getting 12 volts at the relay, then you have a problem before the relay. If this is the case, then you'll have to trace wiring from the fuel pump relay to the fuel pump fuse connections, under the dashboard.