1.7 d-jet '73 almost running Options

[BeatNavy]

So you just put a 2k resistor between wiring harness and ground? How long did it run before running badly? The heads start to heat very quickly, so simply adding resistance won't "help" long while engine warms from ambient temp.

Clean the plugs and try again to see if they foul after a couple of starts. Other than those plugs the symptoms say you may be running way too lean, but it's hard to tell with the info provided.

You'll get there, but you have to be methodical and be sure about things before checking them off as verified.

[isdyl]

Yes, just the resistor between the harness wire and ground. It was just a few seconds of running just to see what would happen.
i think vacuum leaks may be the next thing then. i'll try a bit of brake cleaner spraying.

Thanks for your advice. Dylan

So you just put a 2k resistor between wiring harness and ground? How long did it run before running badly? The heads start to heat very quickly, so simply adding resistance won't "help" long while engine warms from ambient temp.

Clean the plugs and try again to see if they foul after a couple of starts. Other than those plugs the symptoms say you may be running way too lean, but it's hard to tell with the info provided.

You'll get there, but you have to be methodical and be sure about things before checking them off as verified.

[Bmw635]

Check your fuel filter as it may be clogged. I flush the tank and clean filter on a car sat for 23 yrs. Put new fuel in and it washed debris down clogging filter causing choking above 3k rpm then die. Restart rub fine until above 3k rpm , samething happened. Checked filter and it was clogged, clean up then ran up to 5k rpm now.

[isdyl]

Thanks - I've had that on a few previous cars actually, but this one is ok. D

Check your fuel filter as it may be clogged. I flush the tank and clean filter on a car sat for 23 yrs. Put new fuel in and it washed debris down clogging filter causing choking above 3k rpm then die. Restart rub fine until above 3k rpm , samething happened. Checked filter and it was clogged, clean up then ran up to 5k rpm now.

[ctc911ctc]

Hi,

I went down all of the paths that you did with a barn find that had not been running for 30 years.

Djet will only work correctly if the vacuum system is solid.
Repeat after me:
Djet will only work correctly if the vacuum system is solid.

Hate to suggest this but the Plenum is very susceptible to leaks, especially if the car has been in humid geography.

Take the Plenum out and get some plumbing stoppers. Plug it up and pressurize then immerse in water. Mine had a dozen leaks. I welded AND JB Welded (epoxy) the thing. Re-installed in a car that I had already:

Valves Adjusted
Timing
Rebuilt Throttle Body (throttle position switch)
New Fuel Pump
All new hoses
Calibrated Fuel Pressure to 29 psi
rebuilt injectors.
New MPS
New Engine Temps Sensor


When the plenum was complete, the car started, idled, went from 1200 cold to 900 after warmed up.

The next thing I chased was Exhaust leaks. But that is another thread.

[isdyl]

Thanks - ok so I've done a bit of testing this morning and found quite a bad leak around the cold start valve. I put duck tape over the throttle body opening, blocked the AAV, and blew into the MPS hose whilst spraying with leak detection spray. I don't need a cold start valve here as it's quite warm so I removed it and covered the hole with aluminium tape.
It now starts up ok and revs at about 1500rpm. It holds for a couple of seconds but then dies. I'm now wondering if it's getting enough fuel, but when running the fuel pressure stays constant at 29 psi.
Dylan

Hi,

I went down all of the paths that you did with a barn find that had not been running for 30 years.

Djet will only work correctly if the vacuum system is solid.
Repeat after me:
Djet will only work correctly if the vacuum system is solid.

Hate to suggest this but the Plenum is very susceptible to leaks, especially if the car has been in humid geography.

Take the Plenum out and get some plumbing stoppers. Plug it up and pressurize then immerse in water. Mine had a dozen leaks. I welded AND JB Welded (epoxy) the thing. Re-installed in a car that I had already:

Valves Adjusted
Timing
Rebuilt Throttle Body (throttle position switch)
New Fuel Pump
All new hoses
Calibrated Fuel Pressure to 29 psi
rebuilt injectors.
New MPS
New Engine Temps Sensor


When the plenum was complete, the car started, idled, went from 1200 cold to 900 after warmed up.

The next thing I chased was Exhaust leaks. But that is another thread.

[isdyl]

Hi - sorry to keep asking questions - I'm still finding vacuum leaks. There are some around the bakelite spacers between the intake runners and the heads. Should there be gaskets there as well as the spacers please, or would instant (liquid) gasket be ok please? They weren't tightening up properly either as some of the studs had wound out too far and stripped.
Thanks, Dylan

[Bleyseng]

yes, the spacers come with a paper gasket glued to them but I use a liquid gasket sealant when installing them to the heads and intake manifolds.

[ctc911ctc]

Getting all of those leaks will result in a fine running car!

Good Luck! Keep at it!

Hi - sorry to keep asking questions - I'm still finding vacuum leaks. There are some around the bakelite spacers between the intake runners and the heads. Should there be gaskets there as well as the spacers please, or would instant (liquid) gasket be ok please? They weren't tightening up properly either as some of the studs had wound out too far and stripped.
Thanks, Dylan

[euro911]

I didn't read through all the replies so I'll ask: Did you ever spray a 'combustible' liquid or vapor around the motor while it was idling to locate any vacuum leaks? It's the easiest method to find them (IMG:style_emoticons/default/idea.gif)

[isdyl]

Hi, I haven't actually, but that's mainly because it won't stay running. I've definitely got an improvement today after curing some leaks, and now she starts up fine, and idles for about 5 seconds at about 1400rpm, and then starts to die. I can keep the engine running by pumping the throttle, but after a few more seconds she starts to die again. It really feels like the fuel is running out. Pressure gauge stays at 29 psi.
Dylan

I didn't read through all the replies so I'll ask: Did you ever spray a 'combustible' liquid or vapor around the motor while it was idling to locate any vacuum leaks? It's the easiest method to find them (IMG:style_emoticons/default/idea.gif)

[ctc911ctc]

Does it die as if you turned the key off? Or does it stutter and stammer on its way to zero?

Pretty certain that there is a starting phase and then a running phase of the analog logic within the ECU.

CHT? Did you change it? Are you certain that the CHT wire is connected to the ECU?

This is what I would check next. I saw that you measured it cold.

Cheap part, though hard to replace.

Hi, I haven't actually, but that's mainly because it won't stay running. I've definitely got an improvement today after curing some leaks, and now she starts up fine, and idles for about 5 seconds at about 1400rpm, and then starts to die. I can keep the engine running by pumping the throttle, but after a few more seconds she starts to die again. It really feels like the fuel is running out. Pressure gauge stays at 29 psi.
Dylan

I didn't read through all the replies so I'll ask: Did you ever spray a 'combustible' liquid or vapor around the motor while it was idling to locate any vacuum leaks? It's the easiest method to find them (IMG:style_emoticons/default/idea.gif)

[isdyl]

Not quite as quickly as if the key is switched off. I think I need to post an updated video later to see if that demonstrates the current symptoms more clearly.
I measured the CHT from the pin on the ecu loom to the battery earth, so unless the pin isn’t making proper contact with the ecu board maybe?
How critical is the type of fuel filter please? The pressure is showing 2 bar but is it possible the flow could be low even if the pressure shows ok? I currently have a clear plastic inline filter before the pump.
Regards Dylan

Does it die as if you turned the key off? Or does it stutter and stammer on its way to zero?

Pretty certain that there is a starting phase and then a running phase of the analog logic within the ECU.

CHT? Did you change it? Are you certain that the CHT wire is connected to the ECU?

This is what I would check next. I saw that you measured it cold.

Cheap part, though hard to replace.

Hi, I haven't actually, but that's mainly because it won't stay running. I've definitely got an improvement today after curing some leaks, and now she starts up fine, and idles for about 5 seconds at about 1400rpm, and then starts to die. I can keep the engine running by pumping the throttle, but after a few more seconds she starts to die again. It really feels like the fuel is running out. Pressure gauge stays at 29 psi.
Dylan

I didn't read through all the replies so I'll ask: Did you ever spray a 'combustible' liquid or vapor around the motor while it was idling to locate any vacuum leaks? It's the easiest method to find them (IMG:style_emoticons/default/idea.gif)

[isdyl]

Hi - here's a video of it just running out of puff. It's ticking over when I start the video, and then just dies. I restart and it will rev up (not very keenly) but just gradually slows down to a stop if I leave the throttle alone. Any ideas would be much appreciated please!
Dylan

https://www.youtube.com/watch?v=J_-Z8ABsn0Y

[isdyl]

Plugs are very sooty so maybe too much fuel? Question - If the return to the fuel tank was blocked, would this show up as high fuel pressure at the injector rail or not please?
D

[BeatNavy]

You would see abnormally high fuel pressure.

[isdyl]

Thanks

I would love to solve this issue myself but I can see it’s becoming increasingly likely it’s going to need taking to an expert. Last option is to borrow an mps from a friend that I’ve been offered.

You would see abnormally high fuel pressure.

[isdyl]

It's working! It's working!! It was the MPS.

A friend sent me a spare MPS he had and all seems fine now.

Thanks for your help & suggestions. Here she is running:

https://www.youtube.com/watch?v=sKeLNUpHC0I

[BeatNavy]

Was it a blown diaphragm on the MPS? I can't seem to find in this thread anywhere where you verified vacuum on it. Well anyway, good that it's running now.

[isdyl]

I'm not sure - it seems to not leak when you suck it but I haven't tested it with a proper vacuum gauge. The other bad one I had was pretty obvious when it leaked. It actually has a different number on it to the one I've borrowed - mine is 0280100041 and the working borrowed one is 0280100049. From the info I've read on the web both numbers are for a '73 1.7 but I'm not sure about this.

Was it a blown diaphragm on the MPS? I can't seem to find in this thread anywhere where you verified vacuum on it. Well anyway, good that it's running now.