When the engine reaches temperature, it cuts out?

ORTHODR

MEMBER
1991 GMC JIMMY
12,000 MILES

This is actually a boat with a 4.3 l gm v6. When it reaches temp the engine cuts out. Has an HEI distributor. I have changed the control module, rotor, coil, cap and also installed an electric fuel pump all to no avail. Ideas?

Thursday, September 7th, 2023 AT 1:50 PM

5 Replies

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Hi,

I don't know how good I am with boats, but let's give it a try.

When it shuts down, does it start right back up? If it doesn't, have you checked to see if there is a loss of spark and fuel to the engine? If not, let's start there.

If it won't restart, see if it will if you use starting fluid. If it does and then stalls, we'll know its fuel related. If there is no change, then we have to check for an ignition spark at the plugs.

Here is a link that explains how it's done:

https://www.2carpros.com/articles/how-to-check-for-ignition-spark

Let me know what you find. Also, please bear with me. I have no wiring schematics or information for this. I'm hoping I can determine the issue without a manual. LOL Once we know if it is ignition or fuel-related, we can focus on that system.

If you know, let me know the model year of the engine.

Take care,

Joe

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Thursday, September 7th, 2023 AT 6:33 PM

ORTHODR

MEMBER
5 POSTS

It's a 1991 gm 4.3 liter v6. I talked to the dist people ( DUI/Performance distributors), and they think it’s the magnetic pickup failing when it gets hot. I’m picking one up tomorrow but I’m hesitant to remove the distributor until I can get the bost out of the water.

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Thursday, September 7th, 2023 AT 7:36 PM

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Hi,

Absolutely, that can be the cause. Heat can cause all kinds of issues.

If you have a chance, let me know if that resolves the issue. I'm interested in knowing.

Take care,

Joe

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Friday, September 8th, 2023 AT 5:49 PM

ORTHODR

MEMBER
5 POSTS

I completely rebuilt the distributor and it installed easily. It started right up and ran till it reached temperature and stalled. This time it made a sound last an old asthmatic gasping for air. I had put an electric fuel pump on so I replumbed it back to the mechanical pump and it ran like a top. I ran it 20 mins at 3,200 RPMs and no stall.
I think it was a combination of a failed magnetic pickup and fuel starvation as it heated up. I don’t think it was vapor lock although that was one of my early thoughts, hence the electric fuel pump.

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Thursday, September 21st, 2023 AT 11:16 AM

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Hi,

Thanks for the update. I'm glad to know you have it running properly again.

As far as the issue, my money is on the pick-up. Heat can certainly cause them to fail. However, anything is possible.

Regardless, thanks again for the update. Feel free to come back anytime in the future.

Take care,

Joe