The search continues for my mysterious surging idle/stalling issue

[Josh B]

If it were sucking in atf it would be smoking out the tail pipe. He doesn't mention that...

Where would it get ATF?

 

[90B2]

Where would it get ATF?

That was a comment to a post from how far back I don't know. The guy said one of the things that can cause surging is if the modulator valve on the transmission was blown and the engine was sucking transmission fluid through the vacuum line. Just disregard the comment as the original post could have been from a year or more ago.

 

[90B2]

Anyways, here's my .02 on this. If you have a correct ecm, leave it in. I just replaced the ecm in my 90 B2 and there are a few different listings for the 90 and a lot of it depended on Federal emissions or California emissions. I don't know if 87's had a check engine light or not, I believe they should. Have you checked to see if there are any stored codes? There's so much to read through it's easier to ask. Some systems aren't monitored with OBD1. If you have no codes then you have to look at what isn't monitored. One thing I haven't seen mentioned are fuel injectors.

 

[RustyDusty]

Anyways, here's my .02 on this. If you have a correct ecm, leave it in. I just replaced the ecm in my 90 B2 and there are a few different listings for the 90 and a lot of it depended on Federal emissions or California emissions. I don't know if 87's had a check engine light or not, I believe they should. Have you checked to see if there are any stored codes? There's so much to read through it's easier to ask. Some systems aren't monitored with OBD1. If you have no codes then you have to look at what isn't monitored. One thing I haven't seen mentioned are fuel injectors.

My truck doesn't have a check engine light. Ive checked codes, there never were any until I put the new cardone ECM in. With the new ECM I was getting a PIP sensor code so I replaced the whole distributor and the code hasn't returned. I haven't checked for codes lately though.

Previous owner stated the fuel injectors were replaced when him and his son went through the whole truck (about 3 years ago).

 

[90B2]

Ok I sent you a message a few minutes ago, guess you haven't seen it yet.

 

[RustyDusty]

Alright well I’m not sure if this is related or not to the issue at hand but my ranger tried stranding me on a dirt road out near my land. It’s a pretty bumpy and unmaintained and there is no cell reception. I was driving for about 20 minutes without issue when I decided to park the truck near a little lake to walk around. When I got back in I tried to start it and it cranked but wouldn’t start. I tried again, same thing. Then I just turned the key on to listen for the fuel pump prime but it was silent. I popped the hood and looked around for any damaged wires (I’m in the sticks where mice like to make homes under the hood) but everything looked good. I crawled under the truck to make sure the high pressure fuel pump still had both wires connected since the road is so bumpy and it did. Then I disconnected and reconnected the fuel pump relay with the key in the on position to see if I could hear the pump prime but it was silent. Tried a few times without luck. Next I tried unplugging the brown ECM relay and when I plugged it back in I heard the relay click but still no action from the fuel pump. I did this several times until I finally heard the fuel pump prime. I unplugged it and plugged it back in again and no fuel punp sound. I tried starting the truck and it started since the pump just built pressure last time I connected the relay but it immediately died because the pump wasn’t running. I disconnected and reconnected the relay a few more times until I heard the pump prime again and left it connected. Started the truck and it was running fine. Drove it home and now I’m scratching my head.

I’m guessing either my ECM relay is on its way out, I’ve got a wiring issue somewhere over there or my high pressure fuel pump is on its way out. Whenever I check my fuel pressure it’s always spot on. I have yet to verify the state of my in-tank pump and sock. I just assume it’s working if my pressure is good but is it possible for the high pressure pump to get the pressure to the proper specs without help from the low pressure pump? Wondering what you guys think and if this might be connected to my main issue. I have a spare junkyard ECM relay I’m going to keep in the glove box for now just in case.

 

[alwaysFlOoReD]

Almost every frame rail high pressure pump I've had has a bad connection problem at the pump. Look under the rubber boots directly at the pump. Peel them back and replace or lightly squeeze the spade connectors.

 

[rusty ol ranger]

I know on my 87 one of the terminals on the fuel pump relay plug like to push out of the connector when you plug the relay in, but not far enough to actually pop the wire out.

So you end up with a wire that looks connected but is not connected

 

[RustyDusty]

Almost every frame rail high pressure pump I've had has a bad connection problem at the pump. Look under the rubber boots directly at the pump. Peel them back and replace or lightly squeeze the spade connectors.

I did that when the engine wouldn't start. Those connectors do not inspire much confidence. I pulled each wire off and crimped the connectors a bit for a tighter fit.

 

[RustyDusty]

I know on my 87 one of the terminals on the fuel pump relay plug like to push out of the connector when you plug the relay in, but not far enough to actually pop the wire out.

So you end up with a wire that looks connected but is not connected

Ill have to look more closely at the wires. I was under the impression they are crimped to the metal connectors inside the harness but maybe theyre getting loose.