So I have a problem. I’m sure if Fuel or Vacuum or what?

[JSzabo]

I just finished a major maintenance to my Delorean.

Put new spark plugs, all fuel lines replaced.
New updated fuel pump and controller.
New water pump, thermostat.
Belts, pulley bearings.
Oil, oil filter.
Gaskets, o-rings.
Cleaned air manifold, all new bolts and plugs for it.
Rebuilt kjet/fuel system (DMC rebuilt). Fuel manifold cleaned and ungunged.
New clutch line, master clutch cylinder , and slave clutch cylinder.

So we put it back together. Connected all vacuum lines fuel lines.
First we didn’t have the air clearer box on. And it would start then die. Thinking there was still air in the fuel lines. We kept starting and it fired up. Then died. Then fired up then would die. My mechanic friend had me start the car and he pressed down on the fuel pendulum and it would keep running.
Thinking it needed the air cleaner box for better air pressure. We put the the air cleaner box back on. And it would do the same thing start up run for a sec then die. Would do that fine about two more times then wouldn’t even start again. Until we waited about a min and would do the same cycle again.

I believe we have all vacuum lines attached we checked the vacuum canister there was one plug that was kinda rotted away so we plugged it with a new rubber plug and still the same thing.
Not that I believe it has anything to do with it but the bumper is not on.


Any ideas?

[David T]

Sounds like the fuel mixture is too lean. It starts and runs for a moment because of the cold start valve. Once it uses up that fuel it doesn't have enough to run unless you press the plate down. Is the frequency valve buzzing?

[DMC5180]

Well, it’s firing on the initial burst of cold start injection fuel only. It only opens the CSV while the key is in the start position. Considering,the shotgun approach to everything you’ve done to the fuel system. You’ll to verify all the bits are installed correctly. Seems like at this point you need to put a pressure gauge in the fuel system to verify pressures. You replaced the fuel pump. Confirm the lines are correct and the external check valve flow arrow is oriented from the pump. One thing you could try just to confirm fuel pump is flowing enough fuel, is the WUR plug swap to the CSV trick. This is a work around for a bad accumulator HOT Start condition. It will keep the CSV open when you release the key. The engine should stay running but may load up and die. This should allow the all the injector lines to purge. Alternatively you could bypass the the RPM relay, jump the brown and White/Purple wires. The pump will run and you can check fuel pressure resistance on the Air metering flap.

Has the CO screw been touched?

Ha ha, this is my the long winded version of what David T. Stated in basic form.

[JSzabo]

Sounds like the fuel mixture is too lean. It starts and runs for a moment because of the cold start valve. Once it uses up that fuel it doesn't have enough to run unless you press the plate down. Is the frequency valve buzzing?

Yes I believe it is. Me and Brother in law where wondering about that.

[JSzabo]

Well, it’s firing on the initial burst of cold start injection fuel only. It only opens the CSV while the key is in the start position. Considering,the shotgun approach to everything you’ve done to the fuel system. You’ll to verify all the bits are installed correctly. Seems like at this point you need to put a pressure gauge in the fuel system to verify pressures. You replaced the fuel pump. Confirm the lines are correct and the external check valve flow arrow is oriented from the pump. One thing you could try just to confirm fuel pump is flowing enough fuel, is the WUR plug swap to the CSV trick. This is a work around for a bad accumulator HOT Start condition. It will keep the CSV open when you release the key. The engine should stay running but may load up and die. This should allow the all the injector lines to purge. Alternatively you could bypass the the RPM relay, jump the brown and White/Purple wires. The pump will run and you can check fuel pressure resistance on the Air metering flap.

Has the CO screw been touched?

Ha ha, this is my the long winded version of what David T. Stated in basic form.

No, Thank you for all that. I’m getting this all together for things to check. My Brother-In-Law works on Semi Trucks and cars and his and my friend is a great mechanic but we all have never worked on a Volvo engine before. So we are kinda behind the ball with this.

[Bitsyncmaster]

Does it die when you let off the key? That can happen if the white wire on the resistors falls off.

[SS Spoiler]

bet your fuel lines are reversed at the pump....

[JSzabo]

Does it die when you let off the key? That can happen if the white wire on the resistors falls off.

Ya basically. Where would I have to look for that white wire/resistors?

[JSzabo]

bet your fuel lines are reversed at the pump....

Even if the car stays running if we press down on the fuel/air Pendulum?

[Bitsyncmaster]

Even if the car stays running if we press down on the fuel/air Pendulum?

Well if it runs like that it is not the white wire problem.

[mark w]

Low fuel primary pressure or too lean mixture setting.

since the fuel metering unit was rebuilt, the base mixture setting (which is purely mechanical) may need to be reset.

[JSzabo]

Low fuel primary pressure or too lean mixture setting.

since the fuel metering unit was rebuilt, the base mixture setting (which is purely mechanical) may need to be reset.

Is that kinda what David T and DMC5180 are kinda saying? I’m purely trying to connect dots.

Do you know if someone has made a diy or video of how to adjust that?

[David T]

If someone turned the mixture screw, then all that might be necessary is to properly adjust it. If the mixture unit was taken all apart it is possible that adjustment was disturbed. Same for the Primary Pressure Regulator. One of the "O" rings inside could have been damaged or the correct # of shims was not assembled. Again, is the frequency valve buzzing? If it isn't, then that would be the first thing I would work on. If it doesn't buzz, you can't "adjust" your way out of this.

[JSzabo]

If someone turned the mixture screw, then all that might be necessary is to properly adjust it. If the mixture unit was taken all apart it is possible that adjustment was disturbed. Same for the Primary Pressure Regulator. One of the "O" rings inside could have been damaged or the correct # of shims was not assembled. Again, is the frequency valve buzzing? If it isn't, then that would be the first thing I would work on. If it doesn't buzz, you can't "adjust" your way out of this.

Yes the frequency valve was buzzing. What is circled in blue was buzzing.

Is what is circled in yellow where the adjustment for fuel mixture is?

6554965550

[David T]

You are correct on both. Now I would check the injectors to make sure they are flowing equally and each has a good pattern and the seals are not hard, letting air leak.

[mark w]

Yes the frequency valve was buzzing. What is circled in blue was buzzing.

Is what is circled in yellow where the adjustment for fuel mixture is?

6554965550

circled in blue is the Idle Air valve.
circled in yellow, down in that hole is a 3mm hex allen screw, which adjusts fuel mixture. that should only be touched if everything else is in working order.

[DMC5180]

Yes the frequency valve was buzzing. What is circled in blue was buzzing.

Is what is circled in yellow where the adjustment for fuel mixture is?

6554965550

Did, you remove the idle air brass pipe the enters the lower metering housing? If yes make sure the tube is actually inserted in the housing hole. It’s easy to think it was inserted put in reality the tube slid below or beside the port opening. This would be a massive unmetered air leak, causing a very lean condition. The air plate would not move down allowing the fuel pressure to increase and open the injectors. This may explain why you were able to get it to stay running by manual pressing down on the air plate. Did you work the throttle linkage spool by hand when you were doing this?

[JSzabo]

You are correct on both. Now I would check the injectors to make sure they are flowing equally and each has a good pattern and the seals are not hard, letting air leak.

I will have to get into that later on the weekend when I have my Brother-in-law and Mechanic available.


circled in blue is the Idle Air valve.
circled in yellow, down in that hole is a 3mm hex allen screw, which adjusts fuel mixture. that should only be touched if everything else is in working order.

Thanks I won’t touch unless needed too. It looks like something is in the hole. Is that a factory “plug”?


Did, you remove the idle air brass pipe the enters the lower metering housing? If yes make sure the tube is actually inserted in the housing hole. It’s easy to think it was inserted put in reality the tube slid below or beside the port opening. This would be a massive unmetered air leak, causing a very lean condition. The air plate would not move down allowing the fuel pressure to increase and open the injectors. This may explain why you were able to get it to stay running by manual pressing down on the air plate. Did you work the throttle linkage spool by hand when you were doing this?

Yes we did remove the bigger brass pipe under the fuel mixture housing/fuel injection. I didn’t separate the KJet system DMC of Midwest did the separation and reconnection. We will have to check and see to make sure but I believe we put the pipe back in the right spot. Could it have something to do with the o-ring that that pipe goes into? I’m going to have to ask about the throttle linkage. I was in the car starting it.

This video is, of the sounds the car makes after it starting, then dying.


https://youtube.com/shorts/HomKAG6OiM0

[JSzabo]

Does anyone have a video of anyone drilling out or how to remove the CO plug? I’m trying to see how to do it with out taking off the whole Kurt system.

[Helirich]

This thread is interesting because your symptoms are exactly what mine were after cleaning the fuel tank, lines and filter. To be clear, mine would run for a few seconds after releasing the key. Someone suggested mine was running on the start system. I believe this to be true. After pulling my PPV and distroying the O-ring accidently , now I have differnt symptoms. Now mine runs if I rev the engine, but won't idle. I'm currently waiting for new parts.

My theory, the PPV was stuck at a low pressure setting that was below the pressure to spray from the injectors. So it would start on the start system and shut down as soon as it switched to the primary injectors. After I screwed the PPV, it allowed to much pressure on the primary system. So the injectors spray all the time. If I rev the engine, it will run, but if I let it idle, it floods out. I'm hoping the new O-rings will fix it. I should know in a few days.

Please up date this thread if you sort it out.

[David T]

The Workshop Manual has the procedure to remove the tamper-proof plug if it is still in the mixture unit.

[JSzabo]

The Workshop Manual has the procedure to remove the tamper-proof plug if it is still in the mixture unit.

Yes I have the workshop manual. And I have read that. But I wasn’t sure if anyone had a video of it being done or a pictured step by step? My work group would feel better if we seen it done, then do it ourselves.

[JSzabo]

We’ll long time update. But we got the plug drilled out and it is running good.
Video uploading in a few mins.

[JSzabo]

We’ll long time update. But we got the plug drilled out and it is running good.
Video uploading in a few mins.

Here is the Video of it idling on its own with some light revs.


https://youtu.be/7zEN_zHxIrA

[Helirich]

So what was the magic bullet?

[JSzabo]

So what was the magic bullet?

Drilled out the CO Plug and adjustments and it ran great. Even bleed the Coolent system. And drove it around the block.