So this has been an on going battle for my truck 75 k5 with a 95 350 tbi. I put a new ignition control module in it worked for a while then wouldn't start if I went to the store came out and tried to start. Then all of a sudden would just fail when driving till it cool off. I replaced the entire ignition system minus the distributor last weekend. Went to the store by my house this morning literally 2 minute drive wouldn't restart for 5 minutes. Just now went to autozone to buy stuff for my other truck went to grab food from the restaurant next door and won't restart. Been sitting for 20 minutes. I really don't think it's ignition related this time. Is it possible the fuel lines are getting too hot? I'm at a loss I don't want to continue to get stranded every time I drive this thing.
CK5
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crank but no start
- Thread starter white90burb
- Start date
Basics! They'll get you every time.
Next time it won't start, need to know
1. Does it have spark?
2. Does it have fuel spray at the injectors?
Answer those two questions, we can go from there...
On a 90, you should hear the fuel pump come on for 2 seconds, when you turn the key to ON. It's subtle, but, you should be able to hear it.
Next time it won't start, need to know
1. Does it have spark?
2. Does it have fuel spray at the injectors?
Answer those two questions, we can go from there...
On a 90, you should hear the fuel pump come on for 2 seconds, when you turn the key to ON. It's subtle, but, you should be able to hear it.
Hard to diag fuel and spark by myself. The fuel pump is running in have an in line pump on the frame rail. Besides the icm what else would cause no spark or fuel. All my fuses are good and the truck runs great.
Did you put the heat sink compound on the icm?
Sometimes heat can cause weird issues in electrical systems. Could be a fusible link too. I had intermittent no crank issues. The fusible link by the starter was the one deciding when to work...it usually happened after it was hot.
Sometimes heat can cause weird issues in electrical systems. Could be a fusible link too. I had intermittent no crank issues. The fusible link by the starter was the one deciding when to work...it usually happened after it was hot.
Like was said is it spark or fuel. Inline spark tester and check fuel pressure when you have a no start condition. You added an external pump for your TBI in a 75 could be going bad when hot.
You said "minus the distributor",so it still may have a coil that dies after it heats up awhile,or the pick up coil in the distributor is going out,these symptoms are classic for those,and the ignition module dying--runs OK,then starts sputtering,or just stalls without warning..
If a module is installed with no heat sink "grease" under it,it can cause this and fry the module in short order..
Next time it dies,test to see if 12V gets to the coil,the thick red wire on the distributor cap...assuming it does,you need to check further..
You can check for spark by yourself fairly easy if you have some mechanical inclination...
The old "pull off one plug wire and put a old spark plug on it and lay it on the block and crank" test works great--if there is another person to see if its sparking while you crank it over..
You can jump the purple solenoid wire to the positive battery terminal to allow you to crank it over from under the hood,but remember you must have the ignition "on" to get spark!..
If you have access to an "old fashioned" timing light,you can hook that to the battery and a plug wire and watch for spark while cranking-(with the trigger pulled on the timing light!)..
I've taken an old burnt out headlamp bulb and used it as a spark tester--plug one of the plug wires to one terminal,and put a ground wire from the other terminal,to a good ground,the negative battery cable is best--then point the bulb back towards the steering wheel,and crank it over--you'll see if it has spark easily then..
You need to have good consistent spark--sometimes a bad module or pick up coil will make one or two good sparks,then quit--so spin it over a good ten seconds and make sure its consistent..
As for fuel,after it quits you'll have to see if any fuel is getting to the carb --I assume it has a carb if its a '75 truck...a see through fuel filter makes this diagnosis a lot easier--you can take the gas line off and the carb and put it in a soda bottle and crank it over and see if any,and how much fuel gets pumped in...an electric pump should fill it up rapidly (and you dont need to crank it over either)...
If someone hooked it up so its merely assisting the stock mechanical fuel pump,if that one malfunctions it could block or restrict fuel delivery--another bad thing is the electric one could fill your crankcase with gas should the diaphram on the stock fuel pump fails too,which will ruin bearings and rings in a hurry..
It could be your electric pump starts losing pressure after several minutes of run time too,or its maybe one rated for a smaller engine and cant "keep up"..
I had a truck that would die without warning at any time,some days you could go 100 miles with no trouble,it ran perfect--then it would stall like I hit the key..I tried replacing everything I could think of--all the distributor parts,swapped another distributor in it,new fuel pump,checked all the wiring,etc,and each time I replaced something,it ran good and I thought it was "fixed"--till it quit AGAIN..
It turned out I found a small rubber fuel line way back on the frame rail close to the tank,had a "inchworm" loop in it--it was all cracked and brittle,probably original,I cut it off and put a new hunk of hose on it,and that cured it!..I slit the old hose lengthwise and found the inner lining was like bubble gum,all soft,sticky,and separated..I guess it would suck shut on a hard pull or hill and the carb starved for fuel...my next guess was the tank itself was full of some crap clogging the "sock" filter on the sending unit..
A friend bought a '62 Plymouth Valliant that did the same thing,and we replaced practically every part that unbolted on the engine,to no avail--he sold it in disgust...guy that bought it down the street took the tank out and found over a dozen ping-pong balls in the tank!..they would sink and block the "sock" after about 5-10 miles,and you had to pull over and wait a few minutes,then it would re-start and do it again...dumping the balls out "fixed" it..
We wondered if the guy PUT them there,so he could get a good deal on the car--he asked if it was for sale the day my friend got it home!..
..
Hope that helps..
If a module is installed with no heat sink "grease" under it,it can cause this and fry the module in short order..
Next time it dies,test to see if 12V gets to the coil,the thick red wire on the distributor cap...assuming it does,you need to check further..
You can check for spark by yourself fairly easy if you have some mechanical inclination...
The old "pull off one plug wire and put a old spark plug on it and lay it on the block and crank" test works great--if there is another person to see if its sparking while you crank it over..
You can jump the purple solenoid wire to the positive battery terminal to allow you to crank it over from under the hood,but remember you must have the ignition "on" to get spark!..
If you have access to an "old fashioned" timing light,you can hook that to the battery and a plug wire and watch for spark while cranking-(with the trigger pulled on the timing light!)..
I've taken an old burnt out headlamp bulb and used it as a spark tester--plug one of the plug wires to one terminal,and put a ground wire from the other terminal,to a good ground,the negative battery cable is best--then point the bulb back towards the steering wheel,and crank it over--you'll see if it has spark easily then..
You need to have good consistent spark--sometimes a bad module or pick up coil will make one or two good sparks,then quit--so spin it over a good ten seconds and make sure its consistent..
As for fuel,after it quits you'll have to see if any fuel is getting to the carb --I assume it has a carb if its a '75 truck...a see through fuel filter makes this diagnosis a lot easier--you can take the gas line off and the carb and put it in a soda bottle and crank it over and see if any,and how much fuel gets pumped in...an electric pump should fill it up rapidly (and you dont need to crank it over either)...
If someone hooked it up so its merely assisting the stock mechanical fuel pump,if that one malfunctions it could block or restrict fuel delivery--another bad thing is the electric one could fill your crankcase with gas should the diaphram on the stock fuel pump fails too,which will ruin bearings and rings in a hurry..
It could be your electric pump starts losing pressure after several minutes of run time too,or its maybe one rated for a smaller engine and cant "keep up"..
I had a truck that would die without warning at any time,some days you could go 100 miles with no trouble,it ran perfect--then it would stall like I hit the key..I tried replacing everything I could think of--all the distributor parts,swapped another distributor in it,new fuel pump,checked all the wiring,etc,and each time I replaced something,it ran good and I thought it was "fixed"--till it quit AGAIN..
It turned out I found a small rubber fuel line way back on the frame rail close to the tank,had a "inchworm" loop in it--it was all cracked and brittle,probably original,I cut it off and put a new hunk of hose on it,and that cured it!..I slit the old hose lengthwise and found the inner lining was like bubble gum,all soft,sticky,and separated..I guess it would suck shut on a hard pull or hill and the carb starved for fuel...my next guess was the tank itself was full of some crap clogging the "sock" filter on the sending unit..
A friend bought a '62 Plymouth Valliant that did the same thing,and we replaced practically every part that unbolted on the engine,to no avail--he sold it in disgust...guy that bought it down the street took the tank out and found over a dozen ping-pong balls in the tank!..they would sink and block the "sock" after about 5-10 miles,and you had to pull over and wait a few minutes,then it would re-start and do it again...dumping the balls out "fixed" it..
We wondered if the guy PUT them there,so he could get a good deal on the car--he asked if it was for sale the day my friend got it home!..
..Hope that helps..
As mentioned, spark tester will be handy here. You can make one with two wires and a 12V bulb of whatever style you like, but the dash bulbs are easy since the wires are easy to connect to. If you make your own, you can make it long enough to watch while you crank.
FWIW, I had a problem where the truck wouldn't start when it was shut down after getting up to operating temp. Would have to cool way back down (hours) before it could be started again. Turned out to be an injector problem. Not saying replace your injectors, but you could also test your injectors while they are hot and make sure they are within spec, if they are getting an injector pulse.
I cannot remember exactly which ones, but you can also trigger your injectors by jumpering two of the ignition wires.
FWIW, I had a problem where the truck wouldn't start when it was shut down after getting up to operating temp. Would have to cool way back down (hours) before it could be started again. Turned out to be an injector problem. Not saying replace your injectors, but you could also test your injectors while they are hot and make sure they are within spec, if they are getting an injector pulse.
I cannot remember exactly which ones, but you can also trigger your injectors by jumpering two of the ignition wires.
A friend bought a 90's Buick with a 4 cylinder that had a bad fuel injector ,and it too,would sometimes die mysteriously without warning and refuse to re-start...after it cooled some,it would start right up again..
One day it died close to me friends shop,and I pushed it there with my truck--friend went to hook up a noid light to test if the injectors were pulsing and it started !--after he had just tried it seconds before--turned out one injector was evidently shorting to ground inside,which killed power to the other 3...(his car had an injector for each cylinder)..a salvage yard injector fixed it..
I'm guessing this '75 has a later EFI engine in it now ?..
One day it died close to me friends shop,and I pushed it there with my truck--friend went to hook up a noid light to test if the injectors were pulsing and it started !--after he had just tried it seconds before--turned out one injector was evidently shorting to ground inside,which killed power to the other 3...(his car had an injector for each cylinder)..a salvage yard injector fixed it..
I'm guessing this '75 has a later EFI engine in it now ?..
'95 TBI
