Same symptoms, but mine was the fuel pump needing replacement... only a problem on delayed hot restart. After checking everything else, the clue was that the relay for the fuel pump was smoking hot to the touch. I'd fought the problem for over a year -- including with Larry Fletcher's help -- before we changed the fuel and it finally solved the problem.
I would like to close the loop on my Hot Re-start problems and must say that I appreciate all the great help members on this site have been for sharing their experiences and fixes. Thanks Guy's!!! We put a Pressure Gauge on the system, Ref: Carl Rose, and first found that there was a faulty Fuel Accumulator which was not holding the fuel pressure. Changed it, but there still an intermittent problem. Tracked it down to the Control Pressure Regulator or WUR. The WUR was dismantled and found that the bimetallic element had been put back (at some previous time by..?) incorrectly. It was sitting with the pin at an angle to the housing and not functioning properly. When Cold, it would start, the revs rise, and when the engine temperature went up to about 180 degrees, the Cold Start injector would cut out, the revs would drop to about 1,000 rpm. The bimetallic element was not working, but the WUR Housing / Casing temperature went up with the engine heat and caused the injector to stop feeding fuel. The Bimetallic element inside the WUR has been straightened out relative to the Disc and now the WUR works as it should. The Hot start problem has gone away. At least for now!!! I have a 3 day, 1,000 mile rally to do starting on Saturday, so we will see when we get back. Mike at Post #3 was first to suggest a faulty Accumulator. I don't think Too many people would have thought of a badly installed bimetallic element in the WUR! Carl Rose priced a new WUR at $375 in 2004. 2 re-builds of the WUR in my case worked out about the same I guess. We did change all the electrical connectors to the Gold type and put new Rubber boots on as well. Fingers crossed!!! Can't thank you all enough... Karl Robertson
While I did not want to prolong the conversation on "Hot Start" issues, looking at this thread and some others on the site, these issues will continue, I am sure. One of my serious concerns is that a number of parts in the Bosch Fuel System are no longer available from any of the suppliers. There are a few used components from fellow 308 owners or used parts sites, but they are bound to dry up very quickly. Plus we are all hoarders at heart and when there appears to be a forthcoming shortage, we are apt to buy and put away for a rainy day! As a community we need to find a way to put some pressure on the suppliers, or re-source some of the parts from an alternative source. A small but potentially viable business proposition. I know that we have a similar situation that has been filled by Verrell at Unobtainium. I am sure he is not interested in manufacturing Primary Pressure Regulators or Frequency Valves a la Bosch. Maybe someone here can pursue a supplier for these hard to obtain components. Old British cars have a list of suppliers making parts for cars from the 50's for Jaguar, MG, etc. 'Nuff said!
I don't think the WUR is supposed to be wired or plumbed to the cold start injector. I think the cold start injector only gives extra fuel when the engine is cold and the starter is cranking. What you did may have fixed your problem, but I think not for the reasons you think. I'll go check the wiring diagram next time I'm in the garage.
I may be calling it by the wrong name. I picked it up from a post by Carl Rose. Anyway, it is the part in the fuel injection system that has a bimetallic element in it and this has an effect at Cold Start and raises the rpm until engine temperature goes up at which time it controls lowering the rpm down to 1,000 rpm. Long story short, rebuilding it correctly has resulted in fixing the Hot Start problem! We ran it all weekend at a 1,000 mile road rally and it performed flawlessly. Not only that but the fuel consumption was between 18.5 and 19.75 mpg! We ran some great roads in Ohio, Indiana and Kentucky. We were running the cars hard and there were a number of Porsche's trying to keep us honest. I will post that on another thread. And it's not running lean either!! I am happy, to say the least.....
Ref. Carl Rose Ferrari 328 CIS Fuel Pressure Check, July 2004: " For purposes of this article, the control pressure regulator (also known as warm-up regulator or WUR) governs the amount of fuel injected (rich / lean) based on temperature of the internal bimetallic element that closely parallels engine temperature. Incorrect or erratic control pressure can influence fuel mixture & engine running from cold start to warm operating temperature....." Thanks Brian, #31
