89 454 TBI fuel pump question,

Hello, newbie Square body TBI guy.
I drove my new 4 door '89 gem home. On the way, the check engine light came on and the power cuts off, then light on, it roars to life, then repeat, repeat, repeat. So I replaced, cap, rotor, ICM in distributor.
Same issue.
I'll change fuel filter tomorrow.
Question here is. As I have two saddle tanks, do I have "Two electric fuel pumps, inside the tanks"? Anyone know for certain?
Thanks.

Hondo78-

Based on Rockauto's listing for your truck, I'd say 2.

https://www.rockauto.com/en/catalog...fuel+&+air,fuel+pump+&+housing+assembly,10147

Yes, there is a pump in each tank.

Craig 85 said:

Based on Rockauto's listing for your truck, I'd say 2.

https://www.rockauto.com/en/catalog...fuel+&+air,fuel+pump+&+housing+assembly,10147

Click to expand...

Thanks for helping clear that up.

nvrenuf said:

Yes, there is a pump in each tank.

Click to expand...

Thanks for the clarification, I'll order one side and give it a test fit.

Hondo78

One thing to check also is the grounds. I known on my 2010 Denali numerous people have has issues with the main ground cable shorting causing electrical issues. Make sure there is also a ground strap from the engine to the cab and frame.

Better check your ecm fuse. That is exactly what happened on both of my 89's and it was the fuse both times.

Hondo78 said:

Thanks for the clarification, I'll order one side and give it a test fit.

Hondo78

Click to expand...

I ordered a new fuel pump for the driver's side after replacement of the fuel filter didn't solve the issue Friday.
It seems odd, when I accerate to 35 mph, the check engine light came on again and cut power. I even checked it with a trouble code reader, it said no TC codes.

Cartronics said:

Better check your ecm fuse. That is exactly what happened on both of my 89's and it was the fuse both times.

Click to expand...

Thanks cartronics, I'll check it tonight, but if the fuse failed, it shouldn't restart should it?

Craig 85 said:

One thing to check also is the grounds. I known on my 2010 Denali numerous people have has issues with the main ground cable shorting causing electrical issues. Make sure there is also a ground strap from the engine to the cab and frame.

Click to expand...

Craig 85, I'll check the ground tonight, the previous owner just installed a alternator. I'm baffled, and so far changing parts isn't working.

[QUOTE="Hondo78, post: 494346, member: 18654"It seems odd, when I accerate to 35 mph, the check engine light came on again and cut power. I even checked it with a trouble code reader, it said no TC codes.[/QUOTE]

You may put it out there to the forum, but I recall someone saying on TBI trucks the oil pressure is some how connected to the fuel pump system.

Craig 85 said:

[QUOTE="Hondo78, post: 494346, member: 18654"It seems odd, when I accerate to 35 mph, the check engine light came on again and cut power. I even checked it with a trouble code reader, it said no TC codes.

Click to expand...

You may put it out there to the forum, but I recall someone saying on TBI trucks the oil pressure is some how connected to the fuel pump system.[/QUOTE]

Good call Craig, I have been reading about this issue after your post, there is an oil pressure sending unit on some or all of these TBI 88 -91 Square bodies, that shut off if the sending unit behind the distributor fails, and they are prone to it.

I found this response from 2006 Chevytech:

If you pull the fuel pump relay while the engine is running it should keep running. If it dies the oil sender or its wiring is bad or the engine lacks oil pressure.

If you unplug the oil sender while it is running it should keep running also. If it dies the fuel pump relay or it circuit is bad.

Keep in mind there is a redundant circuit (two circuits) supplying power to the fuel pump when the truck is driving down the road.
1 – The oil pressure sender
2 – The fuel pump relay

My 89 is the square body crew-cab, so the fuse and relay are inline somewhere on the firewall, not in an easy to access fuse block. I may find the illusive gray wire to the fuel pump, and put a 12v test jumper on it, If it stops the On Off with the fuel and Check engine light, I have found where to dig.

Another thought or issue; I bought a small coil with my tune up parts, that fits under the rotor and has two wires that come out of the distributor cap, called a distributor pick up coil, I noticed the white plug was mostly melted when I changed the cap and rotor. I taped it up, still works the same as before the tune up, I can't figure out how to change it, the top must come off the distributor or you must take it all the way apart to change this pick up coil?

I need to test every circuit of the ignition, and fuel delivery system I am not so good at this. I need a schematic.

Hondo78 said:

You may put it out there to the forum, but I recall someone saying on TBI trucks the oil pressure is some how connected to the fuel pump system.

Click to expand...

Good call Craig, I have been reading about this issue after your post, there is an oil pressure sending unit on some or all of these TBI 88 -91 Square bodies, that shut off if the sending unit behind the distributor fails, and they are prone to it.

I found this response from 2006 Chevytech:

If you pull the fuel pump relay while the engine is running it should keep running. If it dies the oil sender or its wiring is bad or the engine lacks oil pressure.

If you unplug the oil sender while it is running it should keep running also. If it dies the fuel pump relay or it circuit is bad.

Keep in mind there is a redundant circuit (two circuits) supplying power to the fuel pump when the truck is driving down the road.
1 – The oil pressure sender
2 – The fuel pump relay

My 89 is the square body crew-cab, so the fuse and relay are inline somewhere on the firewall, not in an easy to access fuse block. I may find the illusive gray wire to the fuel pump, and put a 12v test jumper on it, If it stops the On Off with the fuel and Check engine light, I have found where to dig.

Another thought or issue; I bought a small coil with my tune up parts, that fits under the rotor and has two wires that come out of the distributor cap, called a distributor pick up coil, I noticed the white plug was mostly melted when I changed the cap and rotor. I taped it up, still works the same as before the tune up, I can't figure out how to change it, the top must come off the distributor or you must take it all the way apart to change this pick up coil?

I need to test every circuit of the ignition, and fuel delivery system I am not so good at this. I need a schematic.

Click to expand...

you have to remove the dist. from the engine. tap out the pin holding the gear on the bottom, remove the gear, pull the shaft out from the top. ID recommend just buy a new dist. the stock dist. were known for wearing the bushings out for the shaft and allowing them enough movement to make contact with parts in the dist. So for the cost of a new dist you get new bushings, pickup coil, you can sometimes find some that dont have cap rotor or ICM if you have installed yours already. If not return them and get a new dist with cap and rotor.

4WDKC,

That is good advice, the tune up parts cost as much as a rebuilt or new distributor. The 2" pick up coil currently in the distributor does have a melted two wire connector.