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93 rally vandura fuel sensor? fuel relay?

maryskey

By maryskey
in Ask A GM Technician

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maryskey Enthusiast

maryskey

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Cannot seem to figure out what's going on with the van. Have replaced fuel filter and didn't fix problem. Can be driving along perfectly fine at any speed (high or low) and all the sudden speedometer drops and van seems to slip into neutral or something, then almost immediately comes out of it. Have never had any probs with tranny whatsoever. Has been on computer diagnostic twice- no probs there. Went to parts store to buy fuel sensor, but the had nothing listed as such for this van... only a fuel relay. So bought the $12 part anyway but now don't know where it's located on the van. :jester:

GM-Tech Senior Enthusiast

GM-Tech

Posted
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A fuel pump or relay or anything associated with it would not cause the speedo to drop like you described. Even if the engine would quit running while going down the road, the speedometer would keep going.

 

We had LOTS of problems with the bulkhead connector on the older G vans. That the main connector on the firewall, over on the driver's side, above the battery. Typical symptoms were loss of speed signal, no start, stalling, etc.

 

Look at this connector and see if there's a plastic flap of sorts over the top of it. These were less of a problem since that flap deflected water that was a major part of the problem in that connector.

 

You might want to try moving those wires around by hand while the van is idling to see if you can get any sort of reaction. If you do, you're problem is probably there. Even if you can't get it to react, it still may be there.

maryskey Enthusiast

maryskey

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Thank you! I went out and did exactly as you said and no, there is no reaction, tho as you said, the problem may still be there (makes sense after you explained it). So I guess my next question is, what now? Take it to a mechanic... and have them do what? We have a couple of mechanics we trust who have had no success figuring out the problem thus far. Should the wires be replaced, or ??? The van's never given us even a hint of trouble (aside from an alternator) in the yr we've owned it. It was previously owned by the State (a community action program) and they seem to have taken wonderful care of it (judging from the maintenance/repair logs they've kept--which I have read a few times since this prob came up). We recently had a brand new alternator installed (broke down outside of Boston, about 250 miles from home.. not fun.. Pep Boys in NH did the installation).. could that have triggered something with this? Just thinking out loud. I LOVE this van and want to keep it but fear breaking down again if we don't figure out the problem.

GM-Tech Senior Enthusiast

GM-Tech

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That connector has a bolt through the center. If you unscrew that, you can separate the connector and examine the terminals. Be advised that the connector is full of this black gooey stuff that's supposed to help weatherproof it (doesn't work too well I guess!) and it's really nasty to work on.

 

You might find a terminal that looks like it has gotten hot or one that is pushed out so it doesn't stick up into the connector as much as the others. Or, one or more of the female terminals has lost their tension and you have a poor connection.

 

I don't know if this is your problem, but that's one of the problems I remember having with those. I don't see installing an alternator triggering a problem with this connector.

maryskey Enthusiast

maryskey

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Ok, took the thing off and yep, it's goopy inside. Nothing struck me as being wrong... nothing obvious anyway. All the prongs were pretty much level and the female parts didn't look messed up. The only thing that was a little off was the bolt was not exactly tight holding everything in there. I mean it was basically finger loose. So I tightened that right up when I put everything back. The van hasn't done it's "thing" in a couple days.. but then I hadn't touched that part you mentioned until today. So, I am still shrugging my shoulders on this one. A mechanic friend still thinks it's a fuel pump but my intuition is telling me it's electronic not mechanical. Hmm... oh well. Thanks a bunch for your help. :tear:

maryskey Enthusiast

maryskey

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Oops, shouldn't have said "one last question" :P

Called a local GMC dealership and spoke with service dept... the first thing that came to his mind when I mentioned the problem was a speed sensor lcoated at the rear of the transmission. Ring a bell with you? Called local mechanic whom we trust and he says he didn't think 93's had those sensors yet.

GM-Tech Senior Enthusiast

GM-Tech

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I have to apologize because I somehow got the impression that you had an engine problem along with the speedo problem, but in re-reading your first post, it seems to be a tranny problem, not engine.

 

Yes, the 1993 van had a 4L60E trans which is controlled electronically and highly dependent on a speed signal for proper operation. So yes, there is a speed sensor in the trans and it would affect both the speedometer and the trans if it failed.

 

I don't see speed sensors that are intermittent like that. I still think it's more likely that it's wiring, but it could be right at the sensor itself.

maryskey Enthusiast

maryskey

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Well, after contacting several more auto parts stores and another GMC dealership service dept, we finally found the right part(s). One told us it was this part, another told us that part, but neither were actually on the van.. wrong part. Come to find out, there are TWO sensors that we had to get ($48 for the two.. not bad considering we can replace it ourselves). So, we got one out and replaced it just fine, but the other one disintegrated and wound up stuck. Took some digging to get it out but finally did and replaced it. Have not taken the van out yet to test drive it but if this isn't the problem... we are SO at a loss.

maryskey Enthusiast

maryskey

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I've taken the van out about 3-4 times so far (1/2 hr drive or more each time) and it has not done the "thing" it was doing since my husband fixed it. We're taking a longer trip this Sunday and if it doesn't do it then, I will consider the problem solved and fixed! Thanks so much for your help!

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