328 Tough Hot Start

1st diagnostic test is to confirm/deny if it is losing the residual fuel pressure too quickly after warm shut-off. If so, three possible causes:

1. Leaky Accumulator -- remove the return line from vent nipple on end that goes back to the fuel tank. If liquid fuel comes out = replace Accumulator.
2. Leaky check valve on outlet of fuel pump -- if you don't have a leaky Accumulator = cheap enough to replace this part.
3. Leaky o-ring in fuel pressure regulator section of fuel distributor -- if 1 and 2 are OK/fixed, then you go here.

 

I would add a 4th option: leaky fuel injectors. Normally at engine shut off residual pressure for the 328 falls to about 2.6 bar and should hold there for at least 20 minutes. That figure is below the opening pressure for CIS injectors utilized in this model (original Bosch steel injector opening pressure: 3.5 bar, replacement Bosch brass injector opening pressure: 3.8 bar) which prevents any fuel release into the manifold at engine shut down. Minimal injector leaking likely won't drop the residual pressure too quickly but I have worked on injectors with wide open leaks that caused a rapid drop in residual pressure and have resulted in hot start issues.

 

Sorry to maybe oversimplify, but you mention it’s really hot where you are so I have to ask, how much fuel is in your tank? It could be simple vapor lock. If you unscrew your gas cap and hear a little “whoosh” that would confirm it. Sometimes the solution can be really simple and this is an easy one to try.

 

What are you doing with your right foot when you try & start it?

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Steve's advice is right on the money in terms of the order and priority of things to check -- start with the low hanging fruit.

My new-to-me 328 was fine all winter (would drive it ~30 miles every week with prompt hot starts) but in March it started getting fussy with hot starts. It first happened when I got back from a drive and was positioning the car to put on my lift to inspect an oil leak. While I was under there I noticed some fuel varnish on the fuel pump check valve and when I pulled the accumulator vent line there was fuel in it. So I am in the process of replacing the pump and accumulator. Those are the low hanging fruit and not hard to replace. After that you would need to troubleshoot things like the pressure regulator check valve in the metering unit, leaky fuel injectors, and other stuff on top of the engine. For that it usually makes sense to hook up a CIS tester to get some guidance on what to do next.

If it's a typical warm-start vapor lock condition, you can usually get the car started by giving the gas pedal a healthy press while cranking the starter. That would open the throttle and allow enough airflow through the engine to defeat the safety switch, push more fuel through the lines, and purge the vapor. At least that's what I envision it doing based on rusty knowledge of Bosch K-Jet CIS. It has always worked for me.

If you need help with what to look at, let me know, I have taken a lot of pictures recently and also went through the process of finding accumulator and fuel pump replacements. Both are generic Bosch parts but took some effort to find. Ferrari suppliers don't stock any better parts but will sure charge more $$$ for them if they even have them. The original fuel pump part # is NLA and there are 3-4 cross-match units being subbed in.

 

BTW, replacing the pump isn't related to hot start, it just made sense to do while in there replacing the accumulator and dealing with leaks in the pump's plumbing. You can probably get by with just replacing the check valve if everything else looks OK down there.

 

The accumulator is Bosch International # 0 438 170 004. The fuel pump is Bosch USA # 69532 (International # 0 580 464 151 with adapters) or 69435 (International # 0 580 464 125). Both pumps have been substituted in for the NLA original by various suppliers. I have both and will probably flip a coin or do an eyeball fit to decide which one to use.

The pump and accumulator are on a tray accessible through the rear left wheel well after removing the liner. I think it's easiest to remove them as a unit for any replacement work (remove wiring from pump, remove accumulator output hose and pump input hose, then remove three nuts holding the tray down to mounting pads). But as a first test, remove the 1/4" vent hose from the rear of the accumulator and see if there is fuel in it and also see if you can eyeball the check valve and banjo fitting on the forward end of the fuel pump to look for leaks, varnish, etc.

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If you have to remove the pump/accumulator then it means draining the fuel tanks which is an extra chore and requires some caution (it also snowballs into a million other things you could/should do while the tank is drained, which is my current situation). So I'd want strong evidence/suspicion of problems at the pump, check valve, or accumulator before going down that road.

 

Fuel accumulator: Ferrari part# 113978, Bosch part# 0438170004
Fuel pump: Ferrari part# 121727, Bosch part# 0580254947*

*It is my understanding that the Bosch 0580254947 pump is NLA and has been substituted with Bosch part# 0580464125. The -125 pump is what I use on my CIS test bench and can confirm that it produces the correct flow rates and pressures for the 328. Others have confirmed appropriate function/operation of the -125 pump on their 328. See post #20 with confirmation of normal operation after 2 years: New fuel pump 328 | FerrariChat

 

Image Unavailable, Please Login Hello all,
I fully agree with Steve. There is a pressure test that let’s you test the WUR, accumulator, system pressure...
You can download the info from ferrari documentation.
I made my own “tool” using pneumatic banjo bolts, tubbing, gauge and shut-off valve for about $20 if I don’t remember wrong.
Just my opinion

John

 

I had this exact issue
Leaky fuel injectors was the cause

 

i called it a warm start issue
cold start was fine
hot start was fine
wait 10 minutes, warm car would not start. sounded flooded.

 

There are many causes, leaky injectors is certainly one possibility. Just takes one leaking to bleed off pressure from the lines. But I'd try to debug the easier stuff first.

 

I'm about to embark on this same issue with my car. Same exactly symptoms.
I think it’s the accumulator.

about point 1. Is this with a cold car that has not been run in a week or two. Or this should be when the car is warm and not starting?

 

(If the presence of liquid fuel is not just immediately obvious when you remove the hose from the Accumulator vent nipple) It would be best to do this test (looking for liquid fuel coming out of the Accumulator vent nipple) with the fuel pump running, but the engine not running -- i.e., A. unplug the safety switch on the airflow metering device and turn the key "on", or B. remove the fuel pump relay, and use a jumper wire to connect the female 30 terminal in the relay socket to the female 87 terminal in the relay socket (fuel pump runs even with key "off") . Of course, have some provision ready for safely "catching" any liquid fuel that might come out -- e.g., install a short piece of hose onto the vent nipple and run the free end of the hose into an appropriate container.

 

thank you

 

unplugging the cold-start valve worked for me with the 'warm' start issue, the cold-start injector (right top corner) or right next to intake or in front of the oil dip-stick, blue electrical plug, mine seems to be over-active causing the car to flood sometimes after a drive and I want to re-start the car say after sitting for 10 to 20 minutes, hot start no problem, cold-start no problem (with it plugged in)

but unplugging it makes the cold-start more difficult if the car sat for a few days.

cheers

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Today I replaced the pump and accumulator.

I flexed the metal pipe when trying to loose the nuts. Arghhhh
The cap & nut were stuck.

 

One of the biggest concerns when working on things is causing a problem where none previously existed.