TBI 260 Wont Idle When Warm - Will Run other RPM

[RTonelli]

ECU made no difference. Tried running the good motor with the bad motor ECU and other way around both no different.

 

[alldodge]

Swapped ECM, and replaced or swapped everything else.
Compression test good, leak down test good

Its not the harness, so its the injectors or there is a vacuum leak. Might be from under the intake

 

[RTonelli]

I did not do a leak down test - compression yes, and it did hold the pressure but I didn’t do a formal leak down test.
I was thinking of just ordering a Intake manifold gasket and TB base gasket and do those since they’re not expensive and it will cross that off the list

 

[RTonelli]

Here and there I can get it to run good, and if I give it throttle it is quick and responsive, but once it kicks itself into run like crap mode - it starts making a sucking sound from the flame arrestor, and will start to lope like it’s a big cam motor. When it’s doing that if I give it throttle it’ll bog then clean up and rev up, and then will hold a high idle for a few seconds until it comes back down then stalls

 

[alldodge]

Leak down isn't that important
Removing the intake and look at the gasket closely to see if there area areas that have no sealed

Here and there I can get it to run good, and if I give it throttle it is quick and responsive, but once it kicks itself into run like crap mode - it starts making a sucking sound from the flame arrestor, and will start to lope like it’s a big cam motor. When it’s doing that if I give it throttle it’ll bog then clean up and rev up, and then will hold a high idle for a few seconds until it comes back down then stalls

Sounds like injectors might be flooding

 

[RTonelli]

Sounds like injectors might be flooding

That’s what I was thinking, if I remove the arrestor at idle fuel just puddles and pools on top of the flaps. Any ideas what would cause that?

 

[alldodge]

Need injectors cleaned and flow tested

 

[RTonelli]

New intake manifold gasket went on today. Once RTV is dry after work tomorrow I’ll see if that solved anything. If not injectors will be getting sent out to be cleaned and flow tested. Hoping to resolve this once and for all, can’t wait to get it in the water. More to follow tomorrow.

 

[RTonelli]

Video of how it’s acting:

 

[alldodge]

That's a lot of gas

 

[RTonelli]

I agree, my thoughts is vacuum leak somewhere causing the computer to think its getting more air and dumping fuel in - thats why I changed the intake manifold gasket. Agree or you think something else is going on?

I should probably replace the TB base gasket too just to be sure because its only like $10, but I am scared to rip into it as people say they can be a pain to rebuild.

 

[alldodge]

It may just be the injectors are the problem. Only way to know is to have them cleaned and flow tested

 

[RTonelli]

So I started it up, seemed great. All of a sudden after like 10 seconds it’s got a solid beep. Checked codes and it’s code 14 - coolant temp sensor low temp. Then started doing the typical crap.

 

[RTonelli]

The constant beep was a stuck float in the drive reservoir so all good there.
Retimed the motor and it is running much much better. It will randomly get a sucking sound and want to stall but a quick blip of the throttle and then it goes back to idle.

I still need to figure it out because I don’t want to deal with it being intermittent all season.

I know we were thinking it’s running rich but I almost wonder if it’s not getting enough fuel? See the videos below of port motor (good) vs STBD (bad running motor). Almost seems as if it is spraying more on the port motor. Thoughts? I think it’s time to send out for cleaning and flow test. Are there any screens in the TBI throttle body that could be clogging also? Fuel pressure is good.