K2500 wont start

[ricnor]

I have had problems with this before and thought all was now ok but the other day after driving for some time the engine just suddenly cut out altogether and wouldn't attempt to start and hasn't since.
The spark is a bit weak but the fuel pump isn't working , however the pump is ok as I have put a lead directly to the connector at the rear and it bizzes away no problem.
I took the fuel pump relay out and put a volt meter over the 5 terminals and the following is what I got.
Just turn the iginition on and the top left terminal 0.01v. Top right terminal also 0.01v. Bottom left terminal fluctuating between 0.25 and 0.30v. Bottom middle terminal 0v and bottom right terminal 0v

When cranking the engine over - Top left terminal 0.12v Top right terminal 0.10v Bottom right terminal fluctuating between 0.32 and 0.29v middle bottom 0v right bottom 0v

and yes I did have my meter on the correct voltage setting but if nothing is giving anywhere near 12v then surely even with the relay in place it can't send 12v to the fuel pump so the issue would look to be prior to the relay. I have also checked all the fuses and they are all ok. Any one got any ideas as to where to look?

[MT-2500]

Originally Posted by ricnor

I have had problems with this before and thought all was now ok but the other day after driving for some time the engine just suddenly cut out altogether and wouldn't attempt to start and hasn't since.
The spark is a bit weak but the fuel pump isn't working , however the pump is ok as I have put a lead directly to the connector at the rear and it bizzes away no problem.
I took the fuel pump relay out and put a volt meter over the 5 terminals and the following is what I got.
Just turn the iginition on and the top left terminal 0.01v. Top right terminal also 0.01v. Bottom left terminal fluctuating between 0.25 and 0.30v. Bottom middle terminal 0v and bottom right terminal 0v

When cranking the engine over - Top left terminal 0.12v Top right terminal 0.10v Bottom right terminal fluctuating between 0.32 and 0.29v middle bottom 0v right bottom 0v

and yes I did have my meter on the correct voltage setting but if nothing is giving anywhere near 12v then surely even with the relay in place it can't send 12v to the fuel pump so the issue would look to be prior to the relay. I have also checked all the fuses and they are all ok. Any one got any ideas as to where to look?

What year and engine
Have you checked fuses for 12 volts both sides?

With the fuel pump jumped with 12 volts wil it start and what is the fuel pump presure?

[heavymetalmachine]

I went thew this myself...

Clean both batt terminals....

Clean all the grounds..One on the block for the neg cable and there should be another close to the top radiator hose also clean eveything under the plastic cover on the firewall and the block grounds...Bad grounds on these trucks cause all kinds of headaches.... Now on mine it was the ground on the fuel pump itself..I would stop on a hill or in some way or twisting it just right and no pump and no start... I would have someone turn it over as I wiggled the ground wire and it would start up....

Good luck.......

[heavymetalmachine]

O and I would think the batt cable were clean and things would light up but no start then I cleaned the batt and it would fire right up..This happen on my old truck twice a year...

[ricnor]

Sorry forgot to say it is a 1997 454 Vortec 4x4 Auto.

I have given all the earths a good going over and the battery was taken off and charged up plus the terminals cleaned but still no joy.

With the fuel pump powered directly it still wont start.

[MT-2500]

Originally Posted by ricnor

Sorry forgot to say it is a 1997 454 Vortec 4x4 Auto.

I have given all the earths a good going over and the battery was taken off and charged up plus the terminals cleaned but still no joy.

With the fuel pump powered directly it still wont start.

What is the fuel pressure reading?
Will it fire with a shot of carb cleaner?
Still got spark?

[yukon45427]

my trucks doing the same thing i checked the fire going to the pump and replaced the pump twice as long as the tank is on the ground and im cranking the engen the pump works but as soon as i put the tank in i got nothing im going to run a ground from the ground going into the tank today and see if that works ok i just put a ground on and no go i also kooked a lead up to the power wire and the truck fired right up can i run a wire streight to the fuse box for the pump? didnt know if i could get by with that or not thanks

ok i just fixed mine try spliceing into the ground wire and running a wire to the frame thats what just fixed mine

[chevyman_1500_SS]

I want to ask about the spark. In your orginal post you mentioned the spark was there but weak. Have you checked to see of you are arcing from any where? I had a problem where the distributer cap plug wire was arcing to the coil, I used electrical grease and fixed the problem. It's just a different point of view, something to check.