Djet running way too rich... Still! Options

[Halfnelson]

Had a previous thread starting in 2022 about my 73 1.7 standard D-Jet running way too rich and flooding to the point where it wouldn't start. It's been an ongoing issue. I've had a go. 2 garages have had a go. I'm at the point where I'm beginning to lose hope.

A recap. Bought the car 2021, had a problem with intermittent flooding. So far have:
Checked MPS - holding vacuum.
Replaced CHT sensor and tested. Working when flooded.
Replaced fuel pump and tested pressure.
Replaced all vacuum hoses and tested for leaks.
Valves set and rechecked.
New 123 distributor.
New injectors.

Each time I think I've cracked it and it runs and drives - sometimes for a month or so. Then I'll go to start it and it'll flood again to the point where it contaminates the oil. I feel like I've never managed to get to the bottom of the problem. Just keep replacing parts. Thinking maybe a return line that intermittently blocks? I'm kind of at a loss.

[Dave_Darling]

I had an ECU that would open the injectors, but not close them. It was an intermittent problem at first, but then became more frequent as time went on. Apparently an output transistor failing can cause this.

I hydro-locked the engine trying to start it at one point.

--DD

[Halfnelson]

I had an ECU that would open the injectors, but not close them. It was an intermittent problem at first, but then became more frequent as time went on. Apparently an output transistor failing can cause this.

I hydro-locked the engine trying to start it at one point.

--DD

Thanks for the feedback, think I’ll try to source good replacements for ECU and MPS and go from there. If it’s the MPS it would be frustrating as it hold vacuum so that was one of the first things I’d taken off the list of potential culprits, but the feedback suggests they can still be bad so I was almost certainly too optimistic.

[rjames]

I had an ECU that would open the injectors, but not close them. It was an intermittent problem at first, but then became more frequent as time went on. Apparently an output transistor failing can cause this.

I hydro-locked the engine trying to start it at one point.

--DD

Thanks for the feedback, think I’ll try to source good replacements for ECU and MPS and go from there. If it’s the MPS it would be frustrating as it hold vacuum so that was one of the first things I’d taken off the list of potential culprits, but the feedback suggests they can still be bad so I was almost certainly too optimistic.

Another reason why you might want to change the ECU first and independently of the MPS:
MPSs often need to be tuned to match the engine they are mated to. Any replacement MPS you get could run rich or lean before being tuned for your engine.

I'm sure the experts like Jeff B. have seen it more often, but I can only remember one specific instance reported on this site where an MPS that held vacuum seemingly didn't operate correctly.