87 r10 engine and trans problems

[Honky Kong jr]

It's gotta be the gauge, cause the sensor is disconnected. I can find the wire under the truck, but not above. Makes it tough to trace.

Could be the green wire is shorted some where you can't see it or the gauge has given up the ghost.

 

[87ChevyR10]

Could be the green wire is shorted some where you can't see it or the gauge has given up the ghost.

Last time I had the dash apart, I forced the needle back, turned key on and it slowly moved back to the right.

EDIT: Is it coming off the firewall? And is it from the fuse block or elsewhere?

 

[Honky Kong jr]

Last time I had the dash apart, I forced the needle back, turned key on and it slowly moved back to the right.

EDIT: Is it green coming off the firewall? And is it from the fuse block or elsewhere?

It comes out of the bulkhead connector that the engine harness comes from. Take a meter and see if the green wire has continuity to ground if so it's shorted to ground. You should get OL or super high resistance if it's good.

 

[1987 GMC Jimmy]

The p.o. put an aux oil pressure gauge in the truck that has a small clear tube running to the other port behind the distributor. Could this be the issue if the truck doesn't fire up right away and there is no secondary oil pressure circuit telling the pump to run? If so how do I go about fixing it I don't see any cut wires or un used plugs

Hmm... In my '87, you've got the switch behind the distributor and the sender by the filter so you should definitely have that switch behind the distributor. It should be a two wire thing, and I'm surprised there's not an empty plug back there unless it was bypassed somehow. Here's a diagram that's easier to understand than the standard wiring diagram. I'd follow the wiring away from the fuel pump relay per this diagram and see where that takes you. If push comes to shove, just rewire the switch fresh off the B1 ECM pin.

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[87ChevyR10]

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If it’s the lighter green wire, then it’s maxing out OL.

The other green wire bundled to the left is for the tach. I 2 green wires coming from bulkhead connector. The darker one is for the temp sensor. So, I assume the lighter green one (top of bulkhead connector) is for the oil pressure sensor.

EDIT: Wiring diagram says it's a tan wire. I see lots of tan wires...

 

[Torqueshop1]

Removed aux oil pressure gauge replaced with correct sensor and plug (found the 2 plug connector unplugged and buried back there) still Didn't fix the issue.

 

[yevgenievich]

That switch is just a backup for the fuel pump relay

 

[Torqueshop1]

Going to change fuel filter and possibly pump today. The passenger side thank is not used because there is a rust hole in it is there any thing that needs to be done to that to eliminate it from the fuel system

 

[4WDKC]

Going to change fuel filter and possibly pump today. The passenger side thank is not used because there is a rust hole in it is there any thing that needs to be done to that to eliminate it from the fuel system

You can eliminate it if you wish, I prefer to have the dual tanks for longer trips and makes getting gas easier not having to wait for someone to move because you only have a tank that is accessible on one side. Just get this issue fixed then worry about the other tank.

 

[Torqueshop1]

Changed the fuel pump that seemed to fix the starting issue finnaly. I'm guessing the check valve in the pump went out.

Now that it's fixed I'm noticing the truck pulses or surges when I'm at a low speed it idles fine just seems to surge if I'm holding a constant slow speed 10-30 mph. If I give it a little more gas it comes out of it.

Also the cruise control works but it doesn't speed the truck up if I'm going up a hill or something I have to give it gas otherwise my speed will keep dropping

 

[87ChevyR10]

Changed the fuel pump that seemed to fix the starting issue finnaly. I'm guessing the check valve in the pump went out.

Now that it's fixed I'm noticing the truck pulses or surges when I'm at a low speed it idles fine just seems to surge if I'm holding a constant slow speed 10-30 mph. If I give it a little more gas it comes out of it.

Also the cruise control works but it doesn't speed the truck up if I'm going up a hill or something I have to give it gas otherwise my speed will keep dropping

The off idle surging could be the IAC acting up. Mine does the same thing. Give it a bit more gas and it goes away.

 

[1987 GMC Jimmy]

For the cruise control, how do the vacuum lines going to and from the servo look? How does the actual rubber on the servo look?

 

[yevgenievich]

Double check the vacuum. That can affect cruise and surge.

 

[Torqueshop1]

I'm going to check out my cruise servo and vacuum lines today I was digging around behind looking for oil pressure connector so I probably messed something up.

 

[1987 GMC Jimmy]

Those lines can get brittle as hell. It doesn't take much on some of them, and it's good to revise all that stuff.