1993 512tr hot start problem

No, sorry .....

 

Try feathering the gas when she is cranking, it should fire right up. These cars are finiky.. It even says that in the owners booklet..

R

 

Hello,

No such issues here either. Car fires right up hot or cold. Don't know if it makes a difference but mine is a Euro spec car, as such has two less cats than the NA cars. In Canada we're lucky, we can import Euro spec cars as long as they are 15 years old as opposed to 25 in the USA.

Cheers,

Francesco

 

This is possible. There is a check valve on each fuel pump outlet and inside the pressure regulators that should keep the fuel pressure at ~3.8 bar until the engine cools off a bit. Both sides would probably have to be bad, but this is possible as you probably wouldn't notice much of a problem if only one bank failed (i.e., it would still start quasi-OKish on one bank so you don't notice a serious problem until both banks are kaputt). There are other components that can also mess this up, but the bottom line is to measure the fuel pressure on each bank after shutoff to rule this in or out.

The other early thing to rule in or out is ignition -- put a timing light on it during this extend starter motor cranking period and confirm/deny if you have spark.

 

Double threads ... something very similar here: http://www.ferrarichat.com/forum/showthread.php?t=375586

 

Did you fix it by now Tommy ?

 

Any news ?

 

You really should check the resting fuel pressure before anything else. If it cranks and cranks and then eventually fires when its hot, vapor lock will be a problem if there is no fuel pressure.

This is the same problem i currently have ( see other thread ), and my immediate thought was resting fuel pressure caused by bad check valves on the pumps. However, i discovered another issue with my pressure regs was causing similar issue.

Anyways, it takes 10 mins to hook up a pressure gauge on one bank, then the other. The fuel lines are right there.

From page c70 of the manual, u should have 3.4 bar at idle ( there is some blurb in the manual about applying some "suck" and otehrs have quoted 3.8 bar....so say 3.5 to 3.8?) and it should hold 2.7 bar for 1h after u turn the car off. Thats the important part. Anything less than this, then the fuel is escaping somewhere and allowing vapor lock to occur. In my case it was escaping thru the pressure reg back into the intake, but fuel pump check valves are another culprit.

I really would check this. its an easy check...not like my CIS 911 where u need a 4 yr olds hand to connect the gauge etc! Start w easy things first!

 

A leak anywhere in the fuel system will cause a drop in resting fuel pressure. Other than visible leaks ( unlikely as u will have gas/petrol spraying out under running conditions), the three places u could have leaks (and others please chime in if im missing s component) are
1. Fuel pumps. There are 2. One in each tank. There are check valves that hold the fuel in the system in the top of the pumps. If these go bad and start leaking, the resting fuel pressure will drop.
2. Pressure regulators. Right there on the fuel rail. There are two, one per bank. These do not have check valves in them (thx steve) BUT if the diaphragm is compromised, the gas can leak thru that little vac hose back into the intake when shut off. This is the problem i just found on my car. I am waiting for new regs to see if thats my only problem.
3. Leaking fuel injectors. The injectors are the last items in the chain that must hold pressure when the car is switched off. If one or more is leaking, You will lose pressure.

Testing procedures: u will need a decent gauge, and some clamps to carefully clamp off hoses without crushing/tearing them and a helper. Or go to a friends shop that has all this. You must repeat on both banks. Its also 4.30am here...im tired but cant sleep so im writing this...pros will chime in if im wrong or missing something.

1. Fuel pumps. to test the check valves, connect the gauge on the supply side of the fuel system....between the filter and regulator is easiest as its right there. You are gonna clamp between the pressure reg and your gauge. Have helper starter the car ( i dont know if pumps run with ign on only, so start car) u will see running pressure on the gauge of 3.5 bar plus or minus a 0.2 i think from memory. Clamp between the reg and the gauge, switch car off ( have helper do this within a second or two of clamping). Watch gage. It cannot drop below 2.7 bar untill after 1h. If u picture the system in ur mind, what you have just done is simply trap fuel pressure between your gauge and the fuel pump check valve...which is what you want to test. If does drop below 2.7bar, voila theres your problem.

2. Pressure regulator. That little metal thing the gas feeds into after the fuel filter....it has a skinny vac line coming out going to the intake. leave gauge where its at in system, this time your gonna clamp on the filter side of the gauge to check for holding pressure on the injector/pressure regulator side AND on the return side of the system. Idle car, apply clamp to the supply (filter) side, and return line and quickly turn car off. Observe pressure gauge...again you want 3.5-ish at running, with it not going below 2.7b for 1h after shut down. If it does drop below 2.7, now you have to narrow down is it injectors on one bank, or the pressure reg. Do the same operation again, but clamp the little vac line AND the supply gas line AND the return line and observe pressures (you could also just pop off the vac line and see it gas spurts out after shut down, but im playing a professional mechanic this AM dont do that). If you now observe no drops, congrats, its your regulator. Test for sure by popping off the vac line and seeing if gas sprays in your eyes.

3. Injectors. No dice on the other tests? if you have tested ur regulator properly by clamping/plugging the vac line and u still witness a pressure drop below 2.7 before 1h, the only other place that gas can go is out of one or more of the injectors on that bank when the car is switched off.

Others please comment if my procedures are missing a clamp or a component or something!

marcus

 

marcus -- you must have misunderstood me. I wrote:

Haven't thought about how to deduce if it is the check valve in the fuel pump or the check valve in the presure regulator that is bad (if the resting fuel presure falls and it's not leaking out the depression tube going to the intake mainfold), but will this PM.

 

Crapola I did misunderstand. Hmmm. Ill have to think about testing THAT check valve.

Only thing I can thing is you would have to make a test rig, or use an old fuel rail and plug the injector/outbound holes. That sounds like work!

To the OP, sorry dude, I was off the mark, you wont be able to narrow past leaky injectors or the check valve in the pressure regulator. Ill think about it some more tho.

Steve, can I get your opinion, if you have any, on the aftermarket pressure regulators? Part number SPIR301 (google it). To get my Bosch ones might be a while, but i found these aftermarket ones for $100 each which would be nice for at least testing purposes...just wondered if you had any experience.

M

 

+1

Since both check valve are sealing a common volume, the easiest thing I can think of is swapping the pressure regulators and see if the resting fuel pressure problem changes sides (= bad pressure regulator check valve) or stays on the same side (= bad fuel pump check valve).

Be glad to give it a look, but I get nothing that seems right when I google "SPIR301" or "SPIR 301" -- did you mistype the number or can you give a more direct link? Also, do you have the 10-digit Bosch part number for this regulator?

 

Man im not firing on all cylinders today. I meant sipr301. Heres a link...
http://www.amazingsavingsautoparts.com/index.php?action=item&id=10086692
A search on the bosch number brings this up.

Bosch number is 280160525. Found pr301 on amazon for 95 bucks. Just wondered if maybe you had tried the aftermarket pieces. I see ricambi wants $1000 each for the bosch *cough*
I have boschs on order from dave helms too.

Marcus

 

No direct experience for me with that Standard regulator (since I don't have a 512TR ), but I wouldn't be worried about the functionality. If the outer appearance was significantly different from the stock Bosch part, that would be a negative IMO, but I noted that www.ipwparts.com also seems to have the Bosch 0280160525 available for ~$100:

http://www.ipwparts.com/linecardfull.asp?aic=2486&prid=30&desc=Bosch%20Fuel (about 3/4 of the way down the list)

Good hunting!

 

Thx. They have stock on injectors and pumps. No PRs though. I have gone ahead and put all this info and prices in the parts cross sticky for future reference. Thx Steve

 

I have seen a lot of threads about te maintenance of injectors in our F cars.

Mainly the Bosch versions are relatively cheap and very good ...

I will try to help finding these threads ... (one was from Adam SilverGts1988)... :http://www.ferrarichat.com/forum/showthread.php?t=172024&highlight=silvergts&page=3

 

I concur. No fuel should make it out of those vac lines. Search on google or amazon.com for sipr301 or pr301 if u want aftermarket regulators for approx $100 each or you can get bosch ones from reicambi for $1000 each. Othersbmight have bosch in stock for more reasonable $$.

I just got the pr301 part ( cant take a pic, im on a stupid ipad) today...looks exactly the same. I will fit/test tommorow and report back.

Marcus