Starting Problems Options

[nmkimosabe]

I drove my 1974 1.8 briefly after sitting for two months in the winter. It drove fine for the mile or so. I went to drive it the next day and didn't get too far before it chugged, jerked and then died. Had it towed back to my house. Inspected all the vacuum hoses, electrical connections and cleaned the air flow sensor and plug. Starts for a few seconds at times and then dies. Other times it won't even start. Had new plugs, points and fuel filter installed about 10 months ago. I can hear the hum of the fuel pump, so I don't think it's that. Mechanic can't see it for two weeks and I would like to get it running. I would appreciate hearing from the 914 community about similar issues. Thanks.

[wonkipop]

@nmkimosabe

ok

there is one thing that interests me here that you have mentioned.
which i think points to what has about a 90% probability of the problem.

behaviour you have described of interest.
will occasionally fire and run for a very short time.
then repeated cranks and no fire.
and occasionally during that may fire again.

earlier in this thread i mentioned it could be firing off cold start injector but main injectors are not opening. this can happen and produce the symptoms described.

but there is one other cause that will produce a similar response.
and i knew it was something that came up 4 - 5 years ago with another member with an L jet he was going right through.

he discovered by accident his L jet would start with the AFM plug out and it would run for an extended period of time. and along the way the revs would gradually rise. it would run on and on for 2 to 3 even 4 minutes in this state. he asked other members to see if they could duplicate the behaviour. one other member could - that was @StarBear .
but i could not. mine would start, run for 5 -10 seconds and then stop with the AFM plug out. we eventually unravelled the explanation. mine was still bone stock factory with the fuel pump controlled by the AFM. but @StarBear and this particular member's car had had the fuel pump shifted to front of car and wired to run the fuel pump whenever the ignition was on. thats why their cars would run on but mine would simply not continue running. the AFM was not sending the message in my case to keep the pump running.

so with an AFM plug out my car will occasionally fire and run for maybe 5 - 10 seconds.
and then quit. and often with repeated cranking after that will not fire at all.

its all here documented. i found the topic again with a search.
i'm pretty sure this will link to the pages in question with are later in what is a long topic.
its around page 18. read the pages. goes on for about 3 pages.
i fully document a test on my car with how it behaved.

http://www.914world.com/bbs2/index.php?sho...6678&st=320

i've got a feeling there is a very high probability that the harness is shot somewhere in your car. broken wire inside harness? or plug wiring connection. what you have been describing fits the bill.

also its sudden appearance points to something like a wiring failure or component failure all of a sudden. lets not forget these wires, plugs and harnesses are now half a century old.

now i am aware that you say you can get the pump to run by pressing the flapper in with the ignition on. but i suspect you are having to manipulate the AFM up out of position to do so, ie you have the air cleaner up in the air a bit off its base? and if so that may be enough to move the harness to make the contact. but settled back down into its real position its breaking the circuit again. its worth checking out.

and one last thing to check is the throttle position switch.
mounted underneath the throttle body.
check the plug connection to that is thoroughly clean.
the fuel mix at idle in an L jet is in fact controlled by the TPS.
there is a hand over from the TPS to the AFM when the throttle opens.
even though the AFM flapper controls the fuel pump after fire up, the flapper moves just enough, the engine is not running off the AFM at idle, the computer gets its setting off the TPS. after that it does not get fuel settings off the TPS except when it gets to the other end, which is wide open throttle. so just make sure that connection is good.
the TPS is in a vulnerable position as the car ages because a lot of oil vapors can accumulate in the throttle body from the crank case ventilation system and with a worn throttle body it can be that oil and dirt leak down into and around the TPS.

[nmkimosabe]

@nmkimosabe

ok

there is one thing that interests me here that you have mentioned.
which i think points to what has about a 90% probability of the problem.

behaviour you have described of interest.
will occasionally fire and run for a very short time.
then repeated cranks and no fire.
and occasionally during that may fire again.

earlier in this thread i mentioned it could be firing off cold start injector but main injectors are not opening. this can happen and produce the symptoms described.

but there is one other cause that will produce a similar response.
and i knew it was something that came up 4 - 5 years ago with another member with an L jet he was going right through.

Thanks for taking the time to send me these possible issues to review, especially the link. I will keep you posted.

he discovered by accident his L jet would start with the AFM plug out and it would run for an extended period of time. and along the way the revs would gradually rise. it would run on and on for 2 to 3 even 4 minutes in this state. he asked other members to see if they could duplicate the behaviour. one other member could - that was @StarBear .
but i could not. mine would start, run for 5 -10 seconds and then stop with the AFM plug out. we eventually unravelled the explanation. mine was still bone stock factory with the fuel pump controlled by the AFM. but @StarBear and this particular member's car had had the fuel pump shifted to front of car and wired to run the fuel pump whenever the ignition was on. thats why their cars would run on but mine would simply not continue running. the AFM was not sending the message in my case to keep the pump running.

so with an AFM plug out my car will occasionally fire and run for maybe 5 - 10 seconds.
and then quit. and often with repeated cranking after that will not fire at all.

its all here documented. i found the topic again with a search.
i'm pretty sure this will link to the pages in question with are later in what is a long topic.
its around page 18. read the pages. goes on for about 3 pages.
i fully document a test on my car with how it behaved.

http://www.914world.com/bbs2/index.php?sho...6678&st=320

i've got a feeling there is a very high probability that the harness is shot somewhere in your car. broken wire inside harness? or plug wiring connection. what you have been describing fits the bill.

also its sudden appearance points to something like a wiring failure or component failure all of a sudden. lets not forget these wires, plugs and harnesses are now half a century old.

now i am aware that you say you can get the pump to run by pressing the flapper in with the ignition on. but i suspect you are having to manipulate the AFM up out of position to do so, ie you have the air cleaner up in the air a bit off its base? and if so that may be enough to move the harness to make the contact. but settled back down into its real position its breaking the circuit again. its worth checking out.

and one last thing to check is the throttle position switch.
mounted underneath the throttle body.
check the plug connection to that is thoroughly clean.
the fuel mix at idle in an L jet is in fact controlled by the TPS.
there is a hand over from the TPS to the AFM when the throttle opens.
even though the AFM flapper controls the fuel pump after fire up, the flapper moves just enough, the engine is not running off the AFM at idle, the computer gets its setting off the TPS. after that it does not get fuel settings off the TPS except when it gets to the other end, which is wide open throttle. so just make sure that connection is good.
the TPS is in a vulnerable position as the car ages because a lot of oil vapors can accumulate in the throttle body from the crank case ventilation system and with a worn throttle body it can be that oil and dirt leak down into and around the TPS.