Hey guys, My 85 308 QV starts great without needing me to pump the gas pedal when it's cold. It fires right up. However, if I've been driving for a bit and shut it off and then try to restart it, it is harder to start and I need to give it some gas in order to get it going. Any idea what the problem might be? This started recently after a tune up. Thanks! Paul P.S. I had it up to 6500 RPM this morning and it sounded great.
there was a thread on this a while back. do a search on fuel accumulator. there was something about it being full of fumes or some such. my 85 does it sometimes too.
I would definitely suspect the fuel accumulator. Its job is to keep the injection system pressurized for quick starts, the internal diaphragm fails (we see this problem constantly on old Mercedes with CIS injection) leading to having to apply a little throttle on a hot engine to start it. The Bosch part number is 0-438-170-004 I sell them for $210.00 Cheers, Aaron '82 GTSi
Thanks for the info. Can you tell me where the fuel accumulator is located on the engine and is it easy to replace? Anything special i might need to do to replace it? Thanks Paul
the accumulator is on the metal plate with the fuel pump. You get at it most easily through the drivers side rear wheel well. there is a vent line running from the back of accumulator up to the top of the fuel tank. Remove the vent at the accumulator end. If no fuel in the vent line, the accumulator is probably ok. you may be able to jack up the car and remove the vent line from underneath instead of taking off the wheel and liner. the accumulator looks like this...exactly like this http://cgi.ebay.com/ebaymotors/Mercedes-Benz-280-E-450-SE-71-83-Fuel-Pressure-Acc_W0QQitemZ8064924048QQihZ019QQcategoryZ33553QQssPageNameZWD1VQQrdZ1QQcmdZViewItem another possibility is a check valve in the fuel pump, but before springing for parts randomly, suggest you get a cheapo CIS gauge so you can measure the fuel pressure. They are usually around $80. Lots of people sell the same kit for wildly different prices. It looks like this: http://www.sjdiscounttools.com/ta33865.html jcwhitney has a $20 cheaper one, but it's perpetually out of stock. Also not sure if it has the needed fittings. without the gauge, it may be possible to test the accumulator as follows: 1] engine cold, remove the vent line 2] unplug the blue plug on the top of the fuel distributor 3] with your finger over the end of the vent nipple, have someone turn the ignition key to the run position. The fuel pump will start, and the fuel pressure will push the diaphram back in the accumulator. You should be able to feel the air pressure against your finger as the diaphram forces out the air. never tried it, sounds reasonable. All you really care about is two things: 1] the diaphram is not leaking...if it is, fuel will squirt out the vent 2] the diaphram is not stuck note that running the fuel pump without running the engine will not squirt gas into the intake...assuming, or course, something else isn't busted. You will, however, be powering the heating elements in the WUR and AAV when the fuel pump is running, so trying to start the engine immediately afterwards may be a bit hard unless you let those elements cool off again.
There are other possibilities as well such as the WUR bleeding rest pressure off as well as the push valve in the fuel head. So, there are around 5 possible reasons for the rest pressure dropping so dont throw parts at it.
My '85 does the same thing, but according to my owner's manual, this is normal. Just give it a little gas when the engine is hot. Since these are the factory instructions, I don't consider it a problem.
My 308 used to do the same thing. After a complete fuel pressure test, the WUR was the culprit and now all is well.
hi rick, a search will turn up gobs of information...well, if you search for wur instead of wuv Here's a summary: the wur is the warm up regulator, and it's a bit to the right of the throttle body. It messes around with a damping/counter pressure that is applied to a plunger in the fuel metering head. When the wur counter pressure is low, more fuel will get delivered for a given volume of air flowing in the intake. i.e. richer mixture. There is spring in the wur that is heat sensitive. As the wur warms, either by the engine temps or a electrical heating element, the counter pressure is increased, and the mixture is less rich for a given air volume. while the wur was originally for warm up enrichment, some models do altitude compensation and/or enrichment based on engine vacuum, so some purists like to call it a "control pressure regulator" instead. The aav is the auxiliary air valve. Location depends on the car, but it's the gadget mainly responsible for fast idle (not counting the absurd idle on the 80-82 cars). It provides an alternate airway past the throttle plate. In effect, it acts like you are depressing the gas pedal a bit. It also has a heat sensitive spring which closes the airway, and it usually has an electrical heating element along with being mounted in a place where it can be effected by engine temps. In the case of the QV and 328, it's hanging off the bottom of the coolant tank, so when the coolant is hot, the aav stays closed. because of the heating elements, the aav can close and the wur can increase it's counter pressure even when the engine is cold. I mentioned them because if you are running the fuel pump, you are powering those heating elements. Hence, if you let the pump run a while and immediately try and start the car, your fuel mixture will be too lean, and you won't get fast idle. Expect the car to be harder starting and rough idling...you haven't broken anything, and you haven't filled the cylinders with fuel, you've just shifted the cis system outside it's normal operating conditions, and there's no computer (to speak of) to adjust things back for you.
thanx phil. these new fangled injection dealies take an old timer a liitle while to get up to speed. basicly like an automatic choke on a carb.
So here's the latest. My 308 is at the local Ferrari mechanic shop and he first reported that the warm start problem was due to a relay switch which cost $230 (I don't know the name of the actual part but he said it was a relay that is supposed to protect the injection computer). Well, as it turns out, he now believes the injection computer is flakey as well. The new injection computer is going to cost $705. Ouch! This is becoming a very expensive problem to fix. Paul
The new Bosch ECU unit and corresponding relay switch that controls the fuel injection resolved my warm start problem. It was pricey though...$230 for the relay and $705 for the ECU plus three hours of labor. My ECU was flakey...it would be working fine but if you wiggled it or bumped it, it would mess up and it would start running rich. If you bumped it again, the ECU would behave and the fuel injection was back to running correctly. So, this is something good for everyone to think about next time they experience this problem. Paul
did you keep the old parts? I'd love to disassemble them and see what the problem might have been...plus look inside the relay. it appears that besides the fuse, that relay has a zener diode in it. Both of those bits could be added to a standard relay externally. when thumping an electronic device like the ecu does something, it's often a poor solder joint, assuming the connector is ok. Repairing a bad solder joint is easy, but that level of diagnostic is rarely done at a shop unless the parts are unobtainable or extremely expensive relative to the hourly shop rate.
I believe my mechanic told me that the relay I got was the last one in the US (at least at the moment). Some of these parts are going to start getting really hard to find because our cars are getting old and there aren't enough cars on the road to warrant making lots of replacement parts. I can't imagine what it would be like to own a rarer Ferrari. The 308's are as common as they come second only to the 355's and 360's which I understand have eclipsed the manufacturing run of the 308's. It would be nice if the relay and ECU could be made serviceable again should someone need a replacement someday and none are available anymore. Do most of you guys keep your old Ferrari parts as well? Paul
Yes, I keep all of my old parts (much to my wife's dismay). You never know when you or someone else will need just part of some dead remains. The other day, I lost the outside fittings to my 308 antenna. Some other nice FCer had kept those when his antenna gave up the ghost. I got them from him and as a result didn't have to replace my antenna.
