308 Hard Start when warm

Do you think it is flooding out or not getting enough gas? I was told by a mechanic that 308 have a problem with medium warm temperatures (not HOT or Cold) where the cold start will get confused and send too much fuel and flood the engine. Mine does this when it is Very hot outside and the car has been sitting for an hour or so and like you said I have to give the car about half throttle to get it to start. The only fix I can think of is to disconnect the cold start connector (blue connector on the right side of your Manifold connector box). You may try this for a day and see if it solves your problem.

 

It could be many things. It is usually vapor lock or leak down. It could be the fuel accumulator, fuel pump check valve. It could also be leaky injectors or a WUR. It also could be a leaky cold start injector like previously mentioned. The best way to test is by checking your rest pressure.
Accum. test it by removing the vent line. If fuel comes out then the diaphram is leaking.
Check valve is $20 or so. I would replace it and see if it helps.
This should get you going.

 

The QVs have a warm-up regulator, and I'd expect your '81 injected car does also. If it's going bad, that could be the problem, if it doesn't give you the proper fuel-air mix for an already warm car.

 

I feel your pain, same problem with my 83 308, I replaced the accumulator and that didn't fix the problem. next is fuel pump check valve. I'm trying to get the bosh part # DOES SOMEONE KNOW THE CHECK VALVE PART #?
Regards,
Peter

 

The FP check valve info in my notes shows:

F PN 120098 = Bosch 1 587 010 536

as used on the F PN 121727 Fuel Pump (although when I last bought that FP via it's Bosch number it came with that check valve already installed) -- photos below.

Don't know if either the '81 308 or the '83 308 use this setup -- but you could check that yourself at the FerrariUK SPC.

In any case, you've both either got to determine if the fuel supply pressure is dropping too fast after shutoff or keep throwing parts at it

(Assuming the car is running well when warm in every respect except restarting,) If you can figure out a way to run the fuel pump for 10~20 seconds before trying a warm restart this would tell you something (i.e., engine starts right up = more evidence of bad FP check valve and/or accumulator, or no change in behavior = must be something else) -- just a thought...

 

Sam-have you installed fresh fuel filters-that may be the culprit?

Roger B.

 

Just to add to Steve's comments:

The 83' QV has an internal check valve in the fuel pump. In order for the one pictured to work you will need a banjo setup. (this is not how an 83' QV is setup) You will have a union between the steel line and your fuel pump.
This is the correct check valve for 84-85 QVs.

 

i have an extra check valve i got from another Fchatter a while back. Think i paid $10 for it plus shipping, so $15 for it and it is yours. Still sealed, never used.

BOSCH 1 587 010 536

New, sealed bag, and has all three washers of course.

 

I just had the same problem and replaced the fuel accumulator. That seems to have fixed it.

There are a whole lot of threads about this problem and the consensus is that the accumulator is the most frequent culprit.

Try this: next time the car is nice and warm (to the point that the problem would manifest itself), just crank it a bit (1 second is more than enough) then remove the air filter housing and depress 3 or 4 times the large air plate in the fuel distributor. Replace the filter housing and try to start the car. It should start normally.
If, in fact, the car starts that alone would let you avoid some embarassment and also may help in the diagnosing of the problem. The above procedure has never failed and, as I mentioned, my new accumulator fixed the problem.

I used to keep the air filter a little loose so that I could remove without any tools. The whole procedure took no longer that 30 seconds.

Of course, if nothing at all changes, you may want to look into something else but I have a gut feeling...

Please understand that this procedure has been born out of desperation when my car would not start hot and I do not believe it is endorsed by any Ferrari mechanics or otherwise. I am not a mechanic but do work on my car.

A caveat. I purchased my accumulator from Ferrai UK and the everything was good with the exception of shipping; I was charge an INCREDIBLE amount of more than 70 US $ for shipping less than 2 lbs (including packing). That put me at over $ 200 for something I could have purchased for $ 170.00 from the US Ferrari suppliers and possibly a bit cheaper by shopping around. I was under the impression that Ferrari UK would have advised me of the shipping before hand (in which case I would not have bought from them) but the part just showed up at the door a few days after.

Hope the above helps.

 

SOLD

BOSCH 1 587 010 536

to SAM.

 

I too have this problem in a carbed gt4.What could it be and what can I do to fix it? Thanks in advance..........

 

Sorry about digging up this ancient thread, but I am having hot-start problems on my 81 Mondial and have been searching the archives. I tried the above procedure (depressing the plate in the air filter housing), and my car did indeed start. My question is, WHY does pressing the plate down a few times help the car start? It is my understanding that vapor lock is the reason for hot-start prtoblems, and I am not understanding hos pressing the plate a few times with the car off will fix that. Does it somehow cause the injection system to send a slug of liquid fuel through the lines, thus purging the vapor?

 

when you did this, did you leave the key in the run position? If so, I'd guess that pushing down the metering plate is turning on the fuel pump and rebuilding system pressure, plus purging the fuel lines behind the fuel distributor as steve suggested above.

You can accomplish the same thing by putting the key in the run position and disconnecting the blue plug on top of the fuel distributor. That'll power the fuel pump, and has the nice side effect that you won't be dumping fuel into the intake which you will do when pushing down the metering plate (if the fuel pressure is high enough).

that would still just tell you that you have residual pressure problem. Whether it's the accumulator, the wur, the fuel pump check valve or leaky injectors you'd have to figure out.

 

My 77 308 carburetor is the same. Hot starts take lots of pedal pumping..

Cold starts on the the first crank....

??

Greg

 

Quick question about fuel pump operation: In a CORRECTLY functioning K-Jet system, when should the pump run and not run? Am I correct in saying that when the key is on, it should NOT run? And it only starts to run when the car is cranked? Or if you pull the blue plug (safety switch) with the key on, that the pump will then start to run?

Also, when my car is switched on, I hear a constant buzzing sound that seems to be coming from the WUR. It does not seem to be coming from the pump area. Is this normal?

 

My 78 was pretty difficult to hot start as well, but after syncronizing the carbs it became much better and just requires a slight cracking of the throttle now.

 

Pretty sure my carbs are synced properly. Don't think that's it..

??


Greg

 

If it's a heat induced vapor lock situation, have you tried starting it with the gas pedal floored rather than pumping? Don't crank for long as it will flood.

 

I have a UK/Euro spec carburettor 308. Likewise the hot start takes a while, but I think this is normal.

When the car stands with a hot engine the carbs naturally get hot and a amount of fuel vapourisation is normal, particularly around the mixing jets... I understand that is what initially messes up the fueling.

Don't "pump" the pedal as this will activate the accelerator pump jets every time you press down. You want the fuel mix to be leaner for a warm engine, so pumping the pedal will just throw in extra fuel it doesn't need, that is what floods it and will take even longer to clear and start.


I let the engine crank for about 3 seconds, then keep cranking and slowly bring in the throttle, increasing it slowly all the time. The engine just splutters into life everytime by the time I get to about 1/3 throttle - no problem.

If you reckon an engine is flooded (often given away by petrol smell off exhaust)... slowly go to full throttle and wait for about 10 secs, then hold full throttle and crank over the engine for about 10-15secs (or it starts). Then try to start it normally again.



On a cold engine I never bother with the choke, instead I crank the engine long enough to draw a bit of air through the carbs. Then press pedal quickly to the floor twice in succession, repeating every 3 secs and that generally dumps enough fuel from the accelerator jets to start it... Then it is just a case of blipping the throttle to build up the revs. If I'm gentle letting the throttle off, the car will idle from full cold without choke (irrespective of the weather).

I only avoid choke as it tends to soot up the plugs, particularly when and engine isn't getting a lot of running. You only really need the level of enrichment you get with choke when you are starting the engine or if you open the throttle suddenly.

At least that is the theory as it was given to me and it seems to work.


Here's a thing, I've learnt to drive on cars that had carburettors and I've always had somethng with carbs. My little sports car, before the Ferrari, was on a two x twin Weber DCNF set up. So all the little idiosyncrasies seem quite normal to me. We must now be getting the the time where younger drivers have never driven anything except an injection engine, nor had the delight of juggling the choke on a cold damp morning on a Ford Escort that really doesn't want to go... Ahh I'm feeling old now - think I'll shut up.



Long time to start, short time to start... as long as it does actually start you're going to get home!


David.

 

That's likely your "frequency valve" which is right next to your WUR.

 

Everything you said here is OK. For best clarity, I'd put it this way:

1. key "on" (pos II), engine not running, safety switch plugged in and closed = fuel pump does not run
2. key "on" (pos II), engine not running, safety switch unplugged or airflow metering plate depressed (i.e., safety switch open) = fuel pump runs
3. key "start" (pos III) = fuel pump runs (regardless of what's happening with the engine or safety switch).

If "when my car is switched on" = key "on" (pos II), engine not running, safety switch plugged in and closed, this hits me as a little unusual, but I don't have the Mondial8 wiring diagram so can't comment further.

Do the test Phil suggested when you have the problem -- unplug the safety switch, key "on" (confirm you hear the fuel pump running for a few seconds) and then try warm restarting. 2 possible results:

A. If that works -- plug the safety switch back in and try a different ...101 relay in relay position "S" "Fuel injection delivery pump starting relay" when you again have the problem. If that has no effect, you'll need to actually confirm/deny the warm shutoff rest fuel pressure behavior and go after the fuel pump check valve or accumulator if indeed bad.

B. If that doesn't work -- I don't want to go here

 

Thanks for the clarifications so far guys. You all are a HUGE help! Two days ago I did not know the first thing about K-Jet injection, and I am now quickly becoming very comfortable with it. I went out and tried the tests for the fuel pump (plug/unplug the safety wire, etc.). It runs when it should and does not run when it shouldn't.

The buzzing is the frequency valve. You are correct there. Verified with mechanic's stethescope. What is the purpose of the frequency valve?

Warm starting does not seem to be helped with the safety switch unplugged and the fuel pump running before attempting to start. The car still does not want to start. However, if I press down the air flow metering plate for a second or two (with the pump safety plug unplugged and fuel pump running....I have not tried it with safety plug attached) , and then crank the car, it will start immediately. When pressing down on the plate I can hear what sounds like air being purged from the fuel lines. I assume what is happening is I am getting vapor lock due to accumulator/one-way valve/injector leaks, and depressing on the metering plate causes fuel to be pumped through the system, thus purging the trapped vapor through the injectors. Is this a feasible sequence of events?

As mine is a euro model, I don't have a hose on the accumulator drain nipple, so it is tough to tell if I am getting gas leaking back out. I am about to go out to the garage and put piece of scrap hose on it and suspend the hose in a U shape with the open end of the hose at the same height as the nipple. This should catch any draining gas and be evident when I pull the catch hose off.

 

If you have a frequency valve, you really don't have a euro Mondial8 anymore -- you have a euro Mondial8 that has been modified from K-Jet without Lambda to K-Jet with Lambda.

Is the hot restart problem something that is new (and different than it used to be), or has your Mondial8 always had this problem?

 

I think the problem is about 4-5 months old per the previous owner. I just got the car last week, so it is new to me.

I think it may be something of a hybrid, as well. Car is a 1981, has euro VIN, has door plates showing where it was imported to the US in 1984, no cats, no air injection, odometer in kilometers, pressure gauges in bar, but has dual distributors, and now apparently a frequency valve.