What could be wrong ?

[Figoulu]

Hi gents

Back to pagoda issues…

Starting is easy, but idling is impossible…

Tested:
fuel pressure
Smoke leaks… the only result is that it comes from the oil dipstick, and back from air filter => means worn rings ?
Air filter from fip leaks as well, which I understood is normal

Fip has been refurbished with the 7 injectors
Throttle refurbished, no leaks, linkages checked and refurbished, settings between the butterfly and the fip are ok (both in stand position and closed).
Idle screw on the air manifold is closed, but wide open do not change anything
I unplugged the brake booster air duct and obstructed it. No change, and no smoke as well

I’m gonna test the starting aid devices but IMO it comes wether from too rich mixture or too poor air flow. When csv is off car is harder to start (normal)
I was also wondering about a bad fip/ engine timing, need to double check

I know that my cylinders are worn, but leak down test (did it twice to make sur it’s ok) are pretty in the green except 2 cylinders in the -20% range, but still in the green. Compression test are between 10.25 to 13 (did it twice as well).

I don’t wanna touch to the fip until I know that I checked all the possibilities

I enclosed some pics as well as a video that summarises the lasts attempts to start the engine. I do not touch the gas pedal in this video. If I tried I hardly could idle the engine but not less than 2.5 / 3 k rpm, then after like always the engine stalls.

My question is also to know wether worn rings could bring such issues…

https://youtu.be/H1xTW2TmYFU?si=OFPPYXH85D6jB8YH

Thanks for your precious advices…

[stickandrudderman]

Have you done the split linkage test?

[Figoulu]

No. That’s an idea
I will try if the engine can stand more than 5s... 👍

[Harry]

Hello Figoulu,

It would be helpful to understand what precipitated this problem, i.e. had the car been idling OK up to some point and if so, when did it develop the idling problem?  Does it simply die when the accelerator is released or does it stumble for a bit then die?  Have you confirmed the timing is correct?

Unless there is reason to be suspect, I would not imagine the FIP is the contributor.  But it is most important to understand when this problem began to reveal itself and what changes might have been made to the car prior to then.

Harry

[Cees Klumper]

Maybe air in the metal lines from the injection pump to the injectors?

[Figoulu]

Hello Figoulu,

It would be helpful to understand what precipitated this problem, i.e. had the car been idling OK up to some point and if so, when did it develop the idling problem?  Does it simply die when the accelerator is released or does it stumble for a bit then die?  Have you confirmed the timing is correct?

Unless there is reason to be suspect, I would not imagine the FIP is the contributor.  But it is most important to understand when this problem began to reveal itself and what changes might have been made to the car prior to then.

Harry

Not really easy to answer as the car stood in my garage for too long as I’m doing numerous stuff to solve issues…
Well I know that one year ago the engine was idling more or less ok, but just for short tests…
Since then I changed the distributor (123 ignition) and the associated coil, tried to time it as I didn’t have yet a stroboscopic light (bought now, but couldn’t use it yet due to faulty idle)…
In between I worked on cooling system (radiator leaks, water pump, changed the timing chain and tensioner, retimed the engine, tuned the valves, performed my leak down test…)
I would say that it came all of a sudden as if something would have clogged the fuel system for example…
Hard to say in fact…

[Figoulu]

Maybe air in the metal lines from the injection pump to the injectors?

The fuel pressure is Ok (see the video). I had them replated and before putting them back together cleaned them with a galvanised metal wire inside + wd40 + air pressure… it appeared to be a bit rusty inside but since then it’s full with gas…

 If the metal lines would be in cause, why would the engine start, high rev, and then stall ? I don’t see the link

[Figoulu]

I’m carefully reading step by step the bad engine running tour, and already discovered that one spark plug cable was shot. The resistance read about the others are far from being good with about 11/12k ohms per wire. This is not the cause of my troubles but it may not help…

I’m gonna order new ones, it’s the beginning of something

[Figoulu]

Test of the gas pump return volume ok
After 15s this is what I got which is after calculations,1.06L

This is not a clogged pipe or a gas pump default

[rosch]

Looks like a mixture problem to me.
You have ignition at startup ,at least at most cylinders as far as I can judge.
Your engine seems to start easy but won't really pick up and keep running steady.
My guess is  that your engine is initially only running on the fuel supplied by the starting valve (CSV, which is activated for brief period, 1 -12 sec) ,runs at a relatively high RPM ,then  quits.
This could only mean a  temporarily combination of too much fuel and too much air ,otherwise it would not rev-up to 2500 rpm before stalling.

- Start with the linkage tour first to synchronize the FIP and the throttle valve.
- check for a leaking CSV ( letting the electric fuel pump running a few seconds prior to a start attempt may form a small puddle of fuel in the manifold resulting in a rich mixture)
- check if additional , uncontrolled ,air ( leaking hose or gasket ?) is entering the intake manifold
- Check the WRD if the sliding airvalve  works OK.
- check the baro compensator. If it fails ,it usual fails in a " fuel rich" condition.

The easiest way to troubleshoot  mixture and ignition problems is using a Gunson Colortune. Check youtube for some nice  video's which explains it all.


 

[Figoulu]

Thanks so much for your detailed answer. I’m carefully following your 6 detailed épisodes about troubleshootings. Very useful and this is the way I discovered one spark plug wire being wrong…

As I mentioned my linkage is checked already, I changed couple of ball joints and my throttle body has been completely dismantled, refurbished with new gaskets, new axle… so now in a steady position both fpi and throttle are on their stand point. I guess it’s out of the culprit scope… something I could come back later anyway, but I dont feel it's the issue.

Csv has been checked by a pro as well as the fpi and the 6 other injectors. Later yesterday I tested csv with a light and it works for about 1.5s. I have to double check the fact that it leaks or not. But clearly when it’s cut the car starts, but not so easy compared when it’s connected.

I made a smoke detection test and the conclusion is that smoke comes from the air filter of the fip and from the oil dipstick which would mean bad rings. No other leaks from anywhere else. I also have disconneted and neutralized the brake booster air duct, to make sure everything is not forgotten...

Next is the fip, yes… even it has been totally and professionally refurbished recently by a well known specialist, it seems a good lead… I remember that I had to install it back again, because I forgot to put a paper gasket between the block and the FIP… I wonder whether it could be uncorrectly synchronized. could it be that ?

I would also check my coil. I have changed by a new one it when I changed the distributor with a 123 ignition. Could it be possible that the coil would after a short while, stop running?

Then the injectors… I was about to test them according to your test method but didn’t have time to do it yesterday.

I’m also questioning about the yellow color of the gas I have collected in the bottle to test the gas pump volume... Why this colour as I filled the tank (already refurbished) with clear new gasoline…

What do you advice as next step ?
I would go for checking the synchronization of the fip first...

[rosch]

Other possibility is that the FIP was reinstalled 180 degr. out of sync.
This causes fuel being injected at the wrong time,  read : fuel is injected with intake or outflow valve partly open

[Figoulu]

Other possibility is that the FIP was reinstalled 180 degr. out of sync.
This causes fuel being injected at the wrong time,  read : fuel is injected with intake or outflow valve partly open

Agreed... and CSV would be enough to launch the engine and nothing more...
That's a good lead yes...

thank you !