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k5 getting hot and shutting down-please help with some advice

edekgb

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I have a 1988 350 tbi k5- it starts and runs fine for a while then shuts down. It will start back up again right away, runs for a shorter time and stalls again. This will happen about four or five times - each time running time gets shorter and time it takes to start gets longer. I had a new water pump and thermostat put in recently and the new antifreeze levels are fine. Radiator is fine and not getting abnormally hot or boiling over. Any idea what is getting hot and shutting it down? Thanks for any info or ideas in advance.
 
How's the oil pressure and condition of the oil? If the pressure gets low it'll shut the engine off as a safety feature.
 
Engine would only shut off due to low oil pressure if the fuel pump relay has already failed. Oil pressure switch is a fail safe for the fuel pump relay. If the engine cranks and cranks before starting, likely the relay has failed.

When it stalls, is there spark/injector pulse?
 
Yes there is spark and injector pulse but it seems to me to maybe intermitten? Could the coil be going out? I have changed several things out but not the coil or the oil pressure sensor or anything with the oil temp - It has a fresh oil and filter change and it's not low on oil or dosn't leak or burn oil (although I haven't been able to drive it around enough lately to notice if im burning oil).
 
Changed out fuel pump and filter thinking this could be it cuz I was getting kinda low fuel pressure some where around 8-11 and now im getting around 13-15 about. I did not change out the sending unit. My "mechanic" said the unit didn't look to be in to bad a shape and thought we didn't need a new one. Fuel tank and fuel looked pretty clean and not to beat up.
 
What EXACTLY did the impeller blades on the new water pump look like? Left side or right side?

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If you have the stamped blades on the left side, you get to replace your pump again. If you have the fitted impeller like on the right side, you have something else wrong. Perhaps you have the wrong water pump and it is flowing backwards?
 
I gotta say - the shop changed out the waterpump for me when it was in recently. I didn't see the old water pump they took out. I should have asked them to see it but I didn't know and they are pretty trusted shop in the neighborhood so i didn't think to ask them - ive known the guys for years.
 
Lets clarify. Is the truck actually overheating, or are you simply stating that when it warms up, that is when the problem occurs?
 
Truck isn't overheating - I belive something is getting hot and shutting it down a sensor or something (I think) because it seems to do it after running for a while. It starts, runs for a while then stalls. I can start it again right away then runs for a while and shuts down again - does this for a while, maybe four or five times, each time running time gets shorter and shorter and starting gets harder and harder to start (takes longer crank, to get running again) until eventually will not start again until I let it sit for a long while like a few hours and sometimes i will just let it sit and try it the next day. Thing is sometimes it will start cold and sometimes it wont so I gotta try it again the following day. When it does start sometimes I can run it around town for a day or two and sometimes it will stall after sitting for ten mins. INTERMITTEN! :confused: Could this be wiring (wiring harness)?? Thanks again guys. Truck is nice / pretty clean and I have enjoyed driving it around the first year I have had it with little trouble besides getting it to pass emisions early on. Really want to get it running where I don't have to worry in the back of my mind that it could stall on me at any time. I have thrown a lot of parts at it and have had several people look at it without being able to figure it out. I drive off thinking it's fixed only to have it stall on me a day or two later. I have had mechinics tell me they ran it for a while and it's not stalling only to have it stall on me again. With my little mechanic experience and my lack of funds to put it in a shop for troubleshooting hours im stuck.
 
Changed the ignition module. What are the chances I put a faulty one in? Do you guys think it's worth a try to put another new one in? It would seem to be a long shot and I would hate to have to go back and replace parts I have already replaced but if you guys hear alot about faulty new modules do you think im at that point????
 
Chances of having exact same problem with two modules? Not very high.

You can swap parts all day long, but you will need to check the ignition circuitry when it's not working right. Could be pickup, reluctor, coil, you name it. If there is no signal getting to ECM, there will be no injector pulse. Need to make absolutely sure that when it won't start, you are or are not getting that pulse.
 
First thing ... I would check the codes. Free, takes 30 seconds.
 
No codes. Check engine light dosent come on cept for a min when I first put the key in before it starts so the light is operable.
 
It was the fuel sending unit! (I hope?!)

We changed out the fuel pump, and thought the sending unit was in good shape. I had the truck at the shop cuz I was stumped and got tired of it stalling on me all over the place. They droped the tank and found a problem with the wiring - the wire or wires going into the sending unit from over the top and into the tank were corroded or actually the connectors the wires go to were corroded. Has this ever happened to anyone before?

The shop showed me the connections on the sending unit and they were corroded and didn't seem like they could hold the wires on firm, thus causing the intermitten problem until recently the truck not starting at all.

They said I needed a whole new sending unit and that the corodded one could not be fixed. $500 later and the truck is starting but I haven't driven it much since I picked it up yesterday.

Does this sound like it could be the problem and do you think it was best to just have the sending unit replaced or could it have been fixed?
 
If just the connector was corroded the metal contacts could have been cleaned off on both ends of the connector with contact cleaner, style wool, abrasive cloth, etc. Then apply a thin coat of dielectric grease to the metal tabs to prevent that from happening again. Hard to say though without seeing pics. Didn't have to replace the sending unit unless your gas gauge wasn't reading correctly. But maybe it was good that they (hopefully) replaced the fuel pump too since it may have been the original and near its end of life.
 
Well I had replaced the fuel pump very recently and just didn't replace the sending unit - so when I told the shop that, they said they would test the fuel pump and not change it if it is working properly. So they checked it and said it was working fine so they just changed the sending unit. So if that's all it was this whole time I will be happy even spending the $500 cuz I have been trying to figure out this intermitten stalling for a long time.
I have changed out alot of parts trying to figure out what has been wrong with it!!
 
$500 doesn't seem like much to me to drop a tank, diagnose an electrical problem, purchase a replacement sending unit, change the fuel pump into the new send, and reinstall the tank.

If I owned the shop I would have told you for the cost of the part replacement was necessary too. I would say you got a good deal and have an honest mechanic.
 
Just cost me 800 for the same thing you had done. Hopefully it's the fix you needed. Got a deal on that either way.
 
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