97 stumbles when cruising

[SUBURBAN5]

About the same age as the injectors. Was running rough and when I checked fuel pressure it was low enough that I was surprised it even started so I put a pump in. It helped but still wasn't right. Then i discovered the deal with the injectors

Ok sounds like you have a fuel pressure guage. Hook it up. Tape it to your glass and drive your normal route. When it begins to surge, see what your fuel pressure doing. If it starts to hop around , then you have a starting point.

 

[Kevin Callahan]

Ok sounds like you have a fuel pressure guage. Hook it up. Tape it to your glass and drive your normal route. When it begins to surge, see what your fuel pressure doing. If it starts to hop around , then you have a starting point.

Thats a good idea. I'll have to make some sort of extension for the gauge. It's only got maybe 8 inches of line on it

 

[SUBURBAN5]

Thats a good idea. I'll have to make some sort of extension for the gauge. It's only got maybe 8 inches of line on it

Lol I had to do the same thing to mine. In my case when my truck was shuddering. It was because the fuel pump had trash in the sock. New ac delco pump and entire new engine. Never would I suspect the pump to be bad but once a mechanic advise me to try it I saw the fuel drastically drop.

 

[Kevin Callahan]

Lol I had to do the same thing to mine. In my case when my truck was shuddering. It was because the fuel pump had trash in the sock. New ac delco pump and entire new engine. Never would I suspect the pump to be bad but once a mechanic advise me to try it I saw the fuel drastically drop.

I'm going to try to make something and test it out this weekend

 

[SUBURBAN5]

Hopefully it ends up being a simple repair

 

[scott2093]

And I really wish I could monitor torque converter lock up because I'm not so sure that isn't the entire problem is the torque converter locking and unlocking

What model scanner is it?
You could maybe also monitor your brake light switch along with Schurkey's advice..

 

[Kevin Callahan]

What model scanner is it?
You could maybe also monitor your brake light switch along with Schurkey's advice..

it's a innova 3040e I believe. I checked the brake switch and everything looks to be adjusted and in good order there

 

[scott2093]

I checked the brake switch and everything looks to be adjusted and in good order there

You mean on the scanner while the issue happened?

 

[Kevin Callahan]

You mean on the scanner while the issue happened?

I just checked physically to make sure it wasn't loose or out of adjustment. My scanner doesn't have much by way of info like that on it. It will read codes and show me throttle position, 02 sensors and a few other small things

 

[Kevmore007]

I had this almost exact thing happening to my Yukon. Do you still have the stock plastic distributor? I replaced mine with a Summit Racing one and the stumble at cruising is gone.
The gear on the original one was sharp and pointy like a knife edge, not square like new. I went under the hood to wiggle the spark plug wires at the distributor cap and the whole thing lifted up. One of the screw bosses on the plastic distributor was broken and cap was only holding on with one screw.

Vortec Distributors SUM-850098​

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