1.7 d-jet '73 almost running Options

[BeatNavy]

I've heard conflicting things on whether it should hold pressure after shutting off (and how long), and whether there's a check valve in the old 3 port pump to keep up pressure (or not). I really cared when my old engine ALWAYS required two starts (unless I immediately feathered throttle). I figured it was not getting enough fuel initially, and I did notice that my fuel pressure dropped off pretty steadily after shutting off the engine. Having said that, I don't think that was the root cause of the minor issue.

In terms of whether it's an issue for you: if you have a leaking injector that is letting fuel bleed out (both with engine running and not running) that would be an issue - cause an over rich fuel mixture. If you're maintaining pressure while the engine is running and not otherwise leaking fuel anywhere, I wouldn't think it would be a significant problem.

If you suspect fuel delivery might be an issue even after confirming that the injectors are firing, you need to look for some clues. Be careful about chasing your tail though - focus on getting things right in one area (e.g., ignition and timing, then fuel delivery, etc.) and then move on to the next.

If you have a conventional dizzy with points, get a dwell meter.

More reading: https://members.rennlist.com/pbanders/DJetParts.htm

[isdyl]

Thanks very much, and yes I'm on the case re the valve clearances - new feeler gauges just arrived! D

I've heard conflicting things on whether it should hold pressure after shutting off (and how long), and whether there's a check valve in the old 3 port pump to keep up pressure (or not). I really cared when my old engine ALWAYS required two starts (unless I immediately feathered throttle). I figured it was not getting enough fuel initially, and I did notice that my fuel pressure dropped off pretty steadily after shutting off the engine. Having said that, I don't think that was the root cause of the minor issue.

In terms of whether it's an issue for you: if you have a leaking injector that is letting fuel bleed out (both with engine running and not running) that would be an issue - cause an over rich fuel mixture. If you're maintaining pressure while the engine is running and not otherwise leaking fuel anywhere, I wouldn't think it would be a significant problem.

If you suspect fuel delivery might be an issue even after confirming that the injectors are firing, you need to look for some clues. Be careful about chasing your tail though - focus on getting things right in one area (e.g., ignition and timing, then fuel delivery, etc.) and then move on to the next.

If you have a conventional dizzy with points, get a dwell meter.

More reading: https://members.rennlist.com/pbanders/DJetParts.htm

[isdyl]

Hi all,
So I've checked the valve gaps and all were fine. I've just been looking at the distributor now and checking it all works ok but am wondering if the vacuum advance is working - should I be able to move the plate by sucking on the pipe please?
Dylan

[914_teener]

Hi all,
So I've checked the valve gaps and all were fine. I've just been looking at the distributor now and checking it all works ok but am wondering if the vacuum advance is working - should I be able to move the plate by sucking on the pipe please?
Dylan

You should check it like an MPS. Vaccum is no more psi (bar) than manifold vaccum...8-10 psi. You can observe the arm move and it should hold vaccum. If you have a distributor with both retard and advance and one test bad....the can is kaput and good luck finding one that work. This issue is exactly what lead me to get the 123 distributor years ago. Clean the plate and dizzy before you do this test. Sucking on it won.t tell you if it is leaking.

[Bleyseng]

We check a MPS by putting 15 hg of vacuum on them as that's about idle vacuum. Shouldn't leak down in 5 minutes more than a few lbs.

[isdyl]

Thank you. I'll do as you suggest. Dylan

[TheCabinetmaker]

Just because the mps holds vacuum does not mean it's working properly. That just checks the diaphragm for leakage.

[porschetub]

[quote name='isdyl' date='Mar 15 2020, 05:59 AM' post='2794130']
Hi all,
So I've checked the valve gaps and all were fine. I've just been looking at the distributor now and checking it all works ok but am wondering if the vacuum advance is working - should I be able to move the plate by sucking on the pipe please?
Dylan
[/quote

Yes that will confirm that the vacuum canister is working,if no movement don't assume the canister is bad as it may be that the advance plate is gunked up.
You can remove the canister and test it to confirm this is the issue,sometimes you can free up the advance plate with brake clean then lube it but in my experience it is better to dismantle it and clean the two parts properly.
Good luck.

[isdyl]

Thank you for your suggestions. From the video I posted at the beginning it seems to run well at certain revs, which is leading me to think that the advance/retard isn't working properly. If I suck really hard on the advance pipe I can get a tiny bit of movement on the advance 'arm', but not nearly as much movement as I get on another vacuum unit I have from a different car. I'll see if I can free it up, but I imagine the diaphragm is made of some material which has gone hard.
Dylan

[BeatNavy]

Go ahead and take out and clean the dizzy as Porschetub suggested. Take it apart and do a thorough cleaning and lightly lube everything. Check the ground strap between the two advance plates. This is all good maintenance.

I'm not sure the advance arm moves much even when operating properly (IMO it's not a very "gratifying" movement, so to speak, and hard to tell). It could be your problem, and I'll defer to others if they think that, but I generally put this in the category of "drivability" issues (unless it's really bad).

Did you get a dwell meter and set dwell properly? Then, are you confident you know TDC and the timing marks? If it won't stay running without revs, get someone to help you keep it running while you get the light on it.

[isdyl]

Will do, and thanks again for your help.
Dylan

Go ahead and take out and clean the dizzy as Porschetub suggested. Take it apart and do a thorough cleaning and lightly lube everything. Check the ground strap between the two advance plates. This is all good maintenance.

I'm not sure the advance arm moves much even when operating properly (IMO it's not a very "gratifying" movement, so to speak, and hard to tell). It could be your problem, and I'll defer to others if they think that, but I generally put this in the category of "drivability" issues (unless it's really bad).

Did you get a dwell meter and set dwell properly? Then, are you confident you know TDC and the timing marks? If it won't stay running without revs, get someone to help you keep it running while you get the light on it.

[ClayPerrine]

Dylan,

That stuff sat in my garage for years before I sent it to you. The distributor could use a good cleaning. I thought there were two distributors in the stuff I sent. You might try the other one.

Make sure you oil the felt inside the top of the distributor shaft. That lubes the advance mechanism.

Clay

[isdyl]

Thanks Clay - I’ll do all those things. There was just the one distributor but two ecu’s, two throttle bodies and two looms. D

Dylan,

That stuff sat in my garage for years before I sent it to you. The distributor could use a good cleaning. I thought there were two distributors in the stuff I sent. You might try the other one.

Make sure you oil the felt inside the top of the distributor shaft. That lubes the advance mechanism.

Clay

[PCH]

We've recently problem solved the following: Good idle but no power above 3500 rpms. Solved with a new set of trigger points. Old trigger point pick ups were too worn to work properly.

But then, the minute the engine got warm/ hot, it would just stop running. Removed the computer and the insides smelled of burnt electrical. A fellow 914world enthusiast lent us a computer and the problem was solved. Green pea is now running sweeeet!

Good luck and just go down the check lists, item by item.

[isdyl]

Thanks. Actually there is a spare set of trigger points here too. Maybe I'll try swapping them. I can't do much till next weekend now though, although we may all be told to stay at home for a month soon! Dylan

We've recently problem solved the following: Good idle but no power above 3500 rpms. Solved with a new set of trigger points. Old trigger point pick ups were too worn to work properly.

But then, the minute the engine got warm/ hot, it would just stop running. Removed the computer and the insides smelled of burnt electrical. A fellow 914world enthusiast lent us a computer and the problem was solved. Green pea is now running sweeeet!

Good luck and just go down the check lists, item by item.

[isdyl]

Hi,
I've spent a long time trying to improve the running now and think it's running too rich. My CH temp sensor is reading 4000 ohms and I think it should be nearer 2000 ohms. Would this cause it to run rich please, and is it a big job to change it? The wire goes into a hole in the tin but I can't work out if I have to remove the tin to get it out.
Thanks, Dylan

[BeatNavy]

There are some vagaries about which sensor you should be using, but 4000 ohms is probably on the high side with an ambient temperature (car cold) of 60 degrees. If it's colder (e.g., 40 degrees), then that is not necessarily way out of normal range.

What makes you think it's running rich at this point? Did you get the other things checked (dwell, timing, dizzy cleaning, etc.)?

Changing the CHT is a bit of a PITA the first time you do it, and you have to do it very carefully or you can bugger up the threads in the head. Basically you need to get a deepwell 13 mm socket inside that hole in the tin. Your options are either attempt to stuff the wire lead up into the deepwell socket OR grind off the corner of a short socket extension so the lead can go out there. You use the same tool when installing the sensor, but again, need to be VERY careful not to cross thread.

Again, I recommend reading this page, particularly all the parts about CHT (it's covered in several places): https://members.rennlist.com/pbanders/DJetParts.htm

[isdyl]

Hi - yes I'm sure I have the timing & dwell as best as I can get it. It starts easily and revs zoom up to about 2500 revs and it holds there for a while, and then will drop down and 'sort of' tick over at probably 300 rpm - only just running. If I rev the throttle it will go up to 2500 rpm again and can either hold there (on its own) or die down to 300 again. The air screw makes no difference, and the knob on the ecu make a bit of difference, but very little. I removed the plugs and they are very black and sooty, and the exhaust smells rich. This CHTS reading is the only measurement that is not correct so I guess I'm clutching at straws! That web page you posted just now is something I have printed out and have read it quite a lot now!
Thanks, Dylan

There are some vagaries about which sensor you should be using, but 4000 ohms is probably on the high side with an ambient temperature (car cold) of 60 degrees. If it's colder (e.g., 40 degrees), then that is not necessarily way out of normal range.

What makes you think it's running rich at this point? Did you get the other things checked (dwell, timing, dizzy cleaning, etc.)?

Changing the CHT is a bit of a PITA the first time you do it, and you have to do it very carefully or you can bugger up the threads in the head. Basically you need to get a deepwell 13 mm socket inside that hole in the tin. Your options are either attempt to stuff the wire lead up into the deepwell socket OR grind off the corner of a short socket extension so the lead can go out there. You use the same tool when installing the sensor, but again, need to be VERY careful not to cross thread.

Again, I recommend reading this page, particularly all the parts about CHT (it's covered in several places): https://members.rennlist.com/pbanders/DJetParts.htm

[isdyl]

Oh I forgot to say that it will only 'tick over' at 300 rpm if I disconnect the air temp sensor. With that connected it pretty much stalls after the surge to 2500. I know this points to it being lean as this sensor would richen the mixture if unplugged normally, but why the black plugs? D

Hi - yes I'm sure I have the timing & dwell as best as I can get it. It starts easily and revs zoom up to about 2500 revs and it holds there for a while, and then will drop down and 'sort of' tick over at probably 300 rpm - only just running. If I rev the throttle it will go up to 2500 rpm again and can either hold there (on its own) or die down to 300 again. The air screw makes no difference, and the knob on the ecu make a bit of difference, but very little. I removed the plugs and they are very black and sooty, and the exhaust smells rich. This CHTS reading is the only measurement that is not correct so I guess I'm clutching at straws! That web page you posted just now is something I have printed out and have read it quite a lot now!
Thanks, Dylan

There are some vagaries about which sensor you should be using, but 4000 ohms is probably on the high side with an ambient temperature (car cold) of 60 degrees. If it's colder (e.g., 40 degrees), then that is not necessarily way out of normal range.

What makes you think it's running rich at this point? Did you get the other things checked (dwell, timing, dizzy cleaning, etc.)?

Changing the CHT is a bit of a PITA the first time you do it, and you have to do it very carefully or you can bugger up the threads in the head. Basically you need to get a deepwell 13 mm socket inside that hole in the tin. Your options are either attempt to stuff the wire lead up into the deepwell socket OR grind off the corner of a short socket extension so the lead can go out there. You use the same tool when installing the sensor, but again, need to be VERY careful not to cross thread.

Again, I recommend reading this page, particularly all the parts about CHT (it's covered in several places): https://members.rennlist.com/pbanders/DJetParts.htm

[isdyl]

I swapped the sensor out for a 2k resistor just to see but it made it harder to start and worse running. I think I'll take the whole lot apart again and pay more attention to avoid any possible vacuum leaks. I'm almost past it with this car.....