jtrygstad

Taking the injectors to a shop is a good idea. An alternate is that I took my injectors and soaked them in Chemtool B-12 parts cleaner (a one gallon paint can with parts basket in it) for about a day or so. Nasty stuff, so keep the lid on it.

Luis_M

Sounds like your checking that pressure correctly.

The missing bolt at the back of the plenum holds down the plastic air guide to the top of the air flow metering flap. It won't affect vacuum, but without it some unfiltered air could theoretically get in around that junction. When I redid my top end, I got a new seal for this connection, too, since the old one was flattened out and hard.

Doug_B_928

Thanks, guys.

Jadz928

A leak in the air plenum can cause rough idle, stall. Make sure its sealed and the A/F screw gasket is intact.

Doug_B_928

Okay, will do. Thanks!

jpitman2

Depending on cost of cleaning the injectors, you may be better off getting a set of the shorter brass MB models. Seen on ebay at $20 IIRC. I suspect in the end you will need to do all the major bits - accumulator, pump, pressure hoses etc. WUR replacements are very pricey, but some places will reco them. See the ferrari400parts.com web site for spare parts, and how to overhaul some parts.
FWIW, I had some hot start problems with mine in the early days, then I found an electrical plug dangling down beside the rear of the engine - after a bit of a search, I found a socket in the side of the FD, and that fixed the problem for quite a while. Later on it came back - replaced accumulator. So far no FD issues, fires up beautifully stone cold, drives away fine.
jp 83 Euro S AT 54k

Doug_B_928

Thanks, JP, for the info and advice.

Doug_B_928

My next step (from Watson) is to remove the electrical from the cold start injector and see if it is getting power during cranking. Will do that as soon as I can get my wife to turn the key for me while I have my multimeter on the plug.

In the meantime, I was flipping through the WSM and found a bit about a hot start valve (p. 25-12b). The picture is a bit confusing. I couldn't see it on my car. Do all CIS cars have this? I also don't recall reading anything about this in Watson.

tailpipe

Not all CIS has the hot start valve Doug none of mine have the valve.

Doug_B_928

Okay, that's good; one less thing to worry about, thanks!

Seems like the purpose of the Fuel Accumulator is to hold rest pressure. If I don't have any rest pressure, does that seem like a likely culprit for that part? Watson says that everything is interconnected, so it is difficult to isolate one factor. But the most obvious ones seem to me to be Fuel Accumulator for hot start problem and Cold Start Injector for poor cold start.

Luis_M

is rest pressure still zero after replacing the fuel pump check valve? sometimes this check valve is the problem. new accumulators are $200ish

Doug_B_928

Yep.

jpitman2

Mine has a hot start valve - solenoid only powered while cranking and temp is in a specific range. Lowers control to allow more enrichment than the wur will apparently. The sensor failed on me - 20ohms when closed, enough to prevent solenoid firing. New ones are available in US and Europe, but they wanted crazy $$ for shipping. In the end I bought a 944 version which had a different thread (m10x1 instead of M14x1.5). So I got an m14x1.5 plug, drilled and tapped it m10x1, and the sensor now does its job.
jp 83 Euro S AT 54k

tailpipe

Fuel presure can only leak out of a few places the first suspect is the check valve at the pump easy to replace cheap to buy. Second is the fuel presure regulator this one is hard to find but in VWs they put a residual presure valve in the banjo machine screw to keep presure in the fuel dis one of those could be exchanged to help. Third is the injectors hard to find unless you take them out and test them easier just to have them cleaned and know for sure one telltale sign is really black oil in the engine. Fourth is through the cold start injector rare but easy to check cheap to replace any CIS motor at the bone yard will have one. Fifth is through the fuel accumulator if it has a vent the fuel will come out the carbon canister easy to check you will know if its leaking there will be gas all over the PS front wheel don't ask me how I know lol, if the diaphram in the acumulator is ruptured without a vent you will prolly never tell the difference. Sixth place is a fuel line failure easy to check look for fuel on the ground but check close around the engine might be a small leak at the flex lines from body to the engine NOT GOOD. Imho I would start with checking the cold start power supply and ground make sure that is fully functional, its cheap to do just costs you some time it will make the biggest difference in starting next I would replace the check valve at the pump easy and cheap. After that I would look at getting the injectors cleaned a pain in the butt but I have done most of the 6 cars I own and will be doing them in the rest very soon. What exactly are your symptoms of the hard start? A long time turning over before starting or start and stall over and over again ?

Doug_B_928

@ JP, interesting that some cars would come with them; maybe for very hot climates like AU?

@ tailpipe, thank you very much for the detailed info on the possible sources. I've already changed the check valve at the pump and will soon test the electrical for the cold start using a multimeter on the two prongs of the connector while my wife cranks the motor (would be done already but she's been sick). Not sure how to test the ground for this?? I just changed the oil last fall and don't recall it being unusually black. There are no fuel leaks (nothing from the carbon canister or anywhere else). For hot start, the car catches but it's like it has vapour lock. For hot start I use WOT. Sometimes, I guess if it's not hot enough, there's no problem and it would have started fine without WOT. Other times, I guess when the motor is hot enough, the engine sounds like it's clogged and holding WOT helps to blow out the clog and get it running properly. If some of the little things I'm trying don't work I'll take a video of each of the cold and hot start so you can see exactly what is happening.