89 k5 not starting

[jixxerjello]

My 89 k5 350 tbi isn't starting, I've replaced the fuel relay switch, fuel filter and fuel pump. It just cranks but won't turn over. When I spray starting fluid in the throttle body it fires right up for a couple seconds. When I turn the key over I can't hear the fuel pump at all. Anyone got any suggestions? Any help would be great.

 

[4X4HIGH]

IIRC the ignition module also sends the signal for the fuel pump so it could be a bad ignition module. You might want to change it out for a new one and even if it doesn't fix your immediate issue the ignition modules are a famous failure point and it wouldn't hurt to have a spare in the rig with you.

 

[jixxerjello]

Is the ignition module underneath the the distributor? How hard of job is it to replace?

 

[4X4HIGH]

Is the ignition module underneath the the distributor? How hard of job is it to replace?

Yes it is under the distributor cap. It is an easy swap.

 

[jixxerjello]

So I just replaced the ignition module still not starting. I hooked up a wire from the fuel pump relay to the battery and can hear the fuel pump running but still won't start.

 

[4X4HIGH]

Have you checked for spark at the plug wires yet?

 

[jixxerjello]

Would it be a spark issue if it starts when I put a little fuel or starting fluid into the throttle body?

 

[berg76]

Do you see fuel spraying out of the injectors while cranking?

 

[jixxerjello]

There is no fuel spraying from the injectors.

 

[4X4HIGH]

No fuel spray and no fuel pump can now mean that the pick-up coil inside the distributor is bad. This you have to remove the distributor and completely take it apart to replace. I always like doing it and the module at the same time and I'll bet this is your issue.

 

[dyeager535]

You can buy a complete distributor for ~$110.

 

[Gorillajeep]

The one I ma currently working on is doing the same thing. I know the fuel pump is running I can see the injectors firing, but it will not start.

 

[jixxerjello]

So what I just recently noticed by someone sending me a picture of there tank is my tank doesn't have a group wire coming from the sending unit i looked underneath and it got ripped out. So with it not being grounded why would it come on when I run a wire from the relay to the battery? I'm guessing I need a new sending unit now cause of the ground wire not being there.

 

[dyeager535]

So what I just recently noticed by someone sending me a picture of there tank is my tank doesn't have a group wire coming from the sending unit i looked underneath and it got ripped out. So with it not being grounded why would it come on when I run a wire from the relay to the battery? I'm guessing I need a new sending unit now cause of the ground wire not being there.

I suspect the pump is grounded to the sending unit, and the sending unit ground wire is redundant....sending unit lock ring locks into the metal fitting on the fuel tank, so the sender is grounded to the tank. The tank is grounded through any portion of the metal strap that touches it, and the straps are bolted to the frame. That would make sense as to why it runs.

Obviously, with corrosion, that ground path could be compromised, so I can see GM running a redundant ground to ensure long-term function.

 

[berg76]

My pump won't run without that ground wire. It broke on me awhile back from corrosion.

 

[jixxerjello]

Will it run when it's bypassed? Cause u don't have the ground wire it broke off but when I bypass it through the fuel pump relay switch to the battery the pump kicks on but still not getting fuel

 

[berg76]

Will it run when it's bypassed? Cause u don't have the ground wire it broke off but when I bypass it through the fuel pump relay switch to the battery the pump kicks on but still not getting fuel

I didn't try bypassing it because i immediately saw the broken wire. I wouldn't think it would run without that ground. iirc the pump doesn't ground to the sending unit either. It has a plastic bushing at the intake end of the pump and the output on top is connected by the rubber hose. So there is no path for the pump to ground to the sending unit. So it will not ground correctly through the gas tank because it is not bolted to the frame. It is suspended on the straps which i use to have plastic strips between the strap and tank(no longer).

I would get your wires repaired first and see what happens.

This is the top of my tank. Three wires. Fuel level, pump power and ground.

sending unit

• berg76
• Apr 6, 2016

87 tbi sending unit wires

 

[dyeager535]

I didn't try bypassing it because i immediately saw the broken wire. I wouldn't think it would run without that ground. iirc the pump doesn't ground to the sending unit either.

I don't know if there are differences, but this appears to be a TBI sender, the ground wire is clipped to the sender body

Correct on the straps though. AFAIK all of them used the felt-type material between the straps and tanks, pretty hard to get a ground through those. If the tank shifts over a bit though, the straps can contact the tank as the straps sit in a depression. Also forgot the top of the tank had insulating-type material where it contacts the frame crossmembers.