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Tim's Auto Repair
Tim's Auto Repair, mechanic
Category: Chevy
Satisfied Customers: 13261
Experience:  Have owned a repair shop for 25 yrs.
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1991 Chevy 1500 5.0 motor. 5 speed manual.

Resolved Question:

1991 Chevy 1500 5.0 motor. 5 speed manual. will not stay running unless you hold the key in start position. starter still runs. have changed ignition switch with new one, tried new module and coil. checked all fuse. also installed new computer
Submitted: 3 years ago.
Category: Chevy
Expert:  Tim's Auto Repair replied 3 years ago.

hi

i think your problem is the pick-up coil in the distributer.....it isnt sending a signal to the computer that the engine is turning,,thus,not sending a pulse to the injectors.....if it is the pick-up coil,you may concider replacing the complete distributer with a new rebuilt unit,sense the distributer will need to come out and apart to replace the pick-up.....

thanks

 

graphic

 

Customer: replied 3 years ago.
it is getting plenty of fuel, the injectors are pulsing and it will start up and run as long as you keep the ignition switch in the start position. when you let go to the run position it dies. the picture of the distributer you sent is wrong application. my distributer has a module in it with two plugs, one for coil and other goes to computer
Customer: replied 3 years ago.
Expert:  Tim's Auto Repair replied 3 years ago.

yes..i know it is the wrong picture,,but is similer

tell me..with the key on,,do you have battery voltage on the plus side of the coil?

Customer: replied 3 years ago.
yes on the pink wire
Expert:  Tim's Auto Repair replied 3 years ago.

ok

so,,we are loosing either spark or fuel.....

i would doubt us loosing spark,,sense you have the voltage on the pink wire,,,

this would mean we are loosing fuel.....

can you keep it running on starting fluid,or,but spraying gas into the throttle body?

Customer: replied 3 years ago.
I have not tried this. but if i do spray fuel into it and it stays running then what ?
i have checked the fuse for inj a/b circut.
Expert:  Tim's Auto Repair replied 3 years ago.

ok

this could be a couple of things

the oil pressure shut of switch,,it may be bad and killing power to the fuel pump..this is located on the drivers side of the distributer

or,the pick-up coil in the distributer..

thanks

Customer: replied 3 years ago.
ok, the oil pressure is good when starting. also we installed a new tank and pump assembly. fuel pressure is 12 lbs at throttle body. truck has a oil pressure gauge, it shows 30 plus lbs when running. i can hear pump run when i turn on key. what is the purpose of pick up coil in relation to fuel signal ?
Expert:  Tim's Auto Repair replied 3 years ago.

also.

you may concider the fuel pump relay here..it may be getting power only in the start position..so,,check that also//

 

 

ok..when you first turn on the key,,the fuelpump will come on for two seconds,then go off..it wont come on again with the key on,unless the engine is turning....the fuel pump should run all the time when the engine is turning and it has oil pressure......i know you have oil pressure,,but,the switch may be bad,,and not letting power though

the computer knows that the engine is turning from inputs from the ignition module and the pick-up coil

thanks

Customer: replied 3 years ago.
i am a shop owner myself so i know the frustrations...lol this truck is giving me fits. it came in for a transmission rebuild. they drove it here. after getting transmission back in, it would not start. no fuel at first. we then changed fuel pump and tank as an assembly. still no fuel. we then found the throttlebody was clogged up ? this was tore down and rebuilt with new regulator. this solved the fuel issues. now it starts but dies. after a parts change overkill. module, coil. ignition switch, and computer it still wont stay running in run position. i am going to jump the relay to fuel pump and see if it stays running. since it is thanksgiving i am here alone. i cant spray fuel into TB by myself and start it up. i can use my alldata for wiring location.
Expert:  Tim's Auto Repair replied 3 years ago.

ok

sense the transmission was removed,,and this is when the problem started,,,,,be sure to check the oil pressure shut off switch,,it may have got damage to it when the engine layed back,,when the transmission was removed,,it may have hit the firewall

thanks

Tim's Auto Repair, mechanic
Category: Chevy
Satisfied Customers: 13261
Experience: Have owned a repair shop for 25 yrs.
Tim's Auto Repair and 5 other Chevy Specialists are ready to help you
Customer: replied 3 years ago.
thanks for helping me out today. i just need a boost in the right direction. some of these older vehicules cause me problems
Expert:  Tim's Auto Repair replied 3 years ago.

i agree,,they can be agravating

you and you family have a safe and happy thanksgiving

Customer: replied 3 years ago.
Ok i got the truck started, timing in and idles great. must of been a faulty oil sender unit. thanks. Now the new problem. This truck is running good at idle if you turn on blower fan or headlights this will make the engine start cutting out and backfiring if you try to throttle up. alternator was check. we have traced as much of the wire harness as we can looking for a short. any ideas or things in your past that would make a voltage drop when lights or blower is turned on
Expert:  Tim's Auto Repair replied 3 years ago.

yes..

i know you say the alternator was checked...but,,you need to load test the a\alternator.....even if the alternator is putting out enough volts,,it don't seem to be putting out enough amps,,,,,load test it

thanks

Customer: replied 3 years ago.
IT was load checked, we also took off the original and put on another good one, still has the same issue.
I will accept answer when we finish, thanks
Expert:  Tim's Auto Repair replied 3 years ago.

do you have a load tester or a volt meter?

we will check a few things

Customer: replied 3 years ago.
i have a power probe and volt meter. if i put power probe to frame it has 0.2 v. once i turn on blower or headlights gound shows 2 to 5 volts positive
Expert:  Tim's Auto Repair replied 3 years ago.

lets try this....

tell me how many volts is on the batter with the engine running...with no lights or anything on

Customer: replied 3 years ago.
with engine running it shows 14.1 volts. with lights on or blower on it kills engine before i can get back out to battery
Expert:  Tim's Auto Repair replied 3 years ago.

ok

will it stay running if you give it throttle?..do you have anyone to help you,,to keep it running?

Customer: replied 3 years ago.
no one here but me for now. if you throttle with lights on it backfires thru the exhaust, it wont even throttle up with lights on. somehow there is a dead short pulling down the voltage in the ignition circut making it missfire ? with the lights off you cant drive it either, it will start chugging after you get going. i did notice the dash lights flickering when i pumped the clutch pedal hard to the floor
Expert:  Tim's Auto Repair replied 3 years ago.

strange!

make sure you have a good body ground here....perhaps from the negative battery post to the body of the truck......you may not have a good ground

Customer: replied 3 years ago.
ill keep trying, i am glad someone is out there on a sunday like me . i work 7 days a week a lot. i lookeded and there is a strap from battery to the intake of the motor. there are two straps coming from the exhaust to the frame and one to the body for ground, there is not a ground from the battery to the body directly
Expert:  Tim's Auto Repair replied 3 years ago.

sorry for the delay//

if it has one ffrom the engine to the body,,it should be fine..but,make sure it is cclean and tight

Tim's Auto Repair, mechanic
Category: Chevy
Satisfied Customers: 13261
Experience: Have owned a repair shop for 25 yrs.
Tim's Auto Repair and 5 other Chevy Specialists are ready to help you
Customer: replied 3 years ago.
Ok , just got home.. I removed the ground from battery and replaced it with a new one so it goes to motor from one lead and to the frame with another lead. this took care of problem. I used my power probe III and sit in truck with it running i coud apply ground to the frame by the door this made it clear up some , so you was right on about the ground..

I found that there was a splice in the ground cable by the engine that was not very good. By replacing the cable , no more splice, i added the other ground strap from the battery to the body for extra ground. This truck came alive after i got it all hooked up. Even the alternater dash gauge is working.. After 25 to 30 hours of tracing circuts and ignition and timing it was just that darn ground....wow. we need to remember this...lol
Expert:  Tim's Auto Repair replied 3 years ago.

glad you got it

thanks for using justanswer

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Tim's Auto Repair
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7880 Satisfied Customers
Have owned a repair shop for 25 yrs.