Fuel pump problems.

[Grimm]

  Hello all, I have an 88 pioneer and I swapped out the fuel pump yesterday since the old one had a baaaaad crack in the hard lines.

Well after my little swap I went to turn on the truck but to no surprise the new pump didnt prime, so come today I spent the entire good half of the evening testing out the relays and even looking at the ground cable.

I am not too well versed in trucks but am doing my best to learn, so far I have fixed a few problems on this truck and this forum has helped me out greatly without me needing to sign up, but now I am at a point where I am stumped.

The relays are good and the ground after a bit of cleaning up is mediocre at best, and yet no prime in the fuel pump. Any advice or steps I could take to try and make this truck run again?

 

  I originally thought one of the wires on the fuel pump came undone when I was putting it in but that seems very unlikely. And when I plugged in the old fuel pump to the harness to see if IT would prime like it use too, it did nothing. But the float on it worked unlike the new one.

[jdog]

where did you get the pump?

was it a pump/housig assembly?

have you checked for power at the pump?

if no power it could be a bad fuse link, relay, or even a bad pump

Welcome, 4.0 or 2.5?

[Grimm]

@jdog I had no other choice then to get it from Ebay, but it came in like new packaging and wiring and all was good. and it was the entire assembly. The old assembly had a damaged float, the filter was ripped, and the hardlines were cracked past the plate and after the plate the hardlines were hard bent.

I'm still getting use to the multimeter, it seems I get power to it, the harness on the truck side gave off a reading. And I swapped out all the relays for a new one but still nothing.

Its a 4.0 4x4

[eaglescout526]

The harness may show power but the question is, can the harness handle the draw of the pump.  There's lots to do especially if you haven't done all of cruisers tips like the C101(Early 87-88's had this connector) and ground refreshing. Right now does the gauge react to the new sending unit assembly IE go full or empty? Empty on full is an H.O.(High Output) 91-92 sending unit and full on full is the proper Renix sending unit. 

There's lot and lots of info to be learned and i am trying to give a crash course in this post. Renix is AMC's Renault/Bendix Fuel Injection system that is commonly referred to in the 86-90 years. The C101 was crammed full of grease that has hardened over the years and made the electrical contacts less conductive and a lot of problems and issues can be resolved there.

 

Peruse cruisers tips, clean everything, pick up some Mopar contact cleaner, stuff is amazing for cleaning the C101 on the fire wall. 

There is a 25 page epic on testing a lot of the circuitry for an 86 2.5L but there is some good info there that can help. 

Acquire all the knowledge you can about these uncommon trucks and have a metric ton of fun with their simplicity. 

[jdog]

no worries, just trying to help clear items up, do you have power on pin one of the fuel pump relay( pin 30 off of the relay), if so with the fuel pump connector disconnected jumper pin 30 to pin 87 and check for voltage at the fuel pump connector orange wire, ( we need voltage measurements)

[Grimm]

@eaglescout526 the tank IS empty now, should I fill it up and see where that gets me? And some mopar contact cleaner. I will be sure to pick some up when I next go into town. And I have been reading a little into cruisers tips, I've been getting some stuff to relocate the ground.

[eaglescout526]

Ok if the gauge shows empty when you power it on, then you got the right sending unit. If it went to full while empty, then youll have fun screwing with some people saying the truck is a magical gas gainer lol. If you don't hear the pump priming, then chances are filling with some gas won't do the trick.