I hope everyone had a great christmas and new years. I’ve been slowly working away on the k-jet system on my break.
Although I’m pretty sure all the vacuum leaks are fixed on the DMC, she’s still not running right. She is a mission to start, sometimes she will and other times you just flatten the battery trying. When she does start, there is a missfire, sometimes is sounds as if she’s only running on 3 or 4 cylinders.
I’ve tried adjusting the mix and bypassing various things like the idle motor, but I still can’t find any consistency. I posted to the DMC Talk Forum, and someone by the name of Mark has been an amazing resource in getting to know exactly how the K-jet system works and where to look for problems.
At the very crux of it, I need to get a K-jet testing kit. I’m going to buy this one in a few weeks (I’m waiting for my pay to start up again after the holidays). As Mark so elegantly put it, trying to solve K-jet issues without a proper kit is like trying to find electrical faults without a multi-meter.
The DMC Service manual has all the instructions needed for testing the fuel system. See pages 145-150 of the Fuel and Emissions book (book 2) for full info, but I have an excerpt below:
I also had a skype video call with Bill from DMC, as I’d already booked this in before Mark replied. Bill was incredibly helpful and gave me a lot of things I could test while I wait for the K-Jet kit. He also identified the previous owner has used the wrong relay to replace the lambda system relay. Bill focused on the warm up regulator as this controls fuel pressure to the distributor. He suggested I take this off and check for obvious clogs etc. I did this and found the inlet filter was clogged with gasket sealer and the vacuum line was clogged with rust.
I cleaned this out as best as I could. I didn’t want to take it apart as the bolts are very tight and DMC offer a core replacement, so I didn’t want to damage these bolts in case I do need to replace the regulator. I was just going to order one to eliminate this being an issue, but Mark suggested waiting until I have the pressure test kit, as there is no point replacing something if I can’t prove it is faulty (very wise advice).
Mark also suggested testing the cold start valve, as that can be done without the test kit. I unbolted the CSV, put it in a jar and plumbed the regulator back in. I went to give the car a quick crank to see if any fuel went into the jar and was surprised that the car started right up! She didn’t even crank, she just fired up as soon as I turned the key. This has never happened before and confirms my suspicion that she’s running far too rich. I turned her off in case there was fuel spraying everywhere.
I checked the jar, and there was no fuel, so I cranked her again, and again she started the moment I turned the key, she was also running much smoother than before. I turned her off and checked the jar and there was very little fuel in there.
Mark has given me some instructions around testing the Cold Start Valve without having to crank the engine, so I’ll give this a go next.
Part 2: The Carburetor…
A few months ago, when I was really getting frustrated with the K-Jet system, I started trying to find some help locally, as I’ve spent over $10,000 on the car so far, and she still can’t even move under her own power. I started talking to local mechanics, and none of them could help. As soon as I mentioned “Bosch K-jetronic Fuel Injection System” they would cringe and say they couldn’t help. My local mechanic suggested converting it to a carburetor.
DMC had been very helpful at this point, but it is cumbersome communicating with people in other timezones, and I wished there was someone who could just physically come and look at the car. I also felt like I was relying too heavily on other people and wanted to do as much as I could myself.
I started looking around for a carbureted manifold for the PRV engine to use as a back up plan. My idea was if I get completely stuck with the K-Jet, I can just put a carb on her. The more research I did on this option, the more attractive it seemed. By using a carb, I could simplify the system a lot as I can get rid of the following components:
- 2x ECU’s
- Cold start system
- Warm up regulator
- Lambda system and sensors
- Throttle microswitches
- Fuel Mix unit
- Fuel Distributor
- 10-ish Injection lines
- Fuel Injectors
- Fuel accumulator
This would also free up a hell of a lot more room in the engine bay, as currently I can barely fit everything back in (the idle motor for example).
As time went on I got more serious about the carb option, but I found the intake manifolds for PRV’s are very rare. I tried contacting people like Bill Robertson, but never heard replies. Eventually just before Christmas I got a message from somone facebook asking if I was still looking for a manifold. I said yes and long story short I got put into contact with a gentleman in Australia who collects Peugeots.
He has spare manifolds and carbs that fit the PRV V6 engine and seeing as how rare these things are (By this point I’d been looking for about 6 months) I agreed to buy one from him. Garry was incredibly helpful, he matched a Weber carb to the manifold, rebuilt the carb and tested it on a PRV. It’s in the mail at the moment and just needs a new air cleaner when it arrives. I think I’ll also paint the manifold.
Gary even gave me a call and stepped me through everything I needed to do to hook it up and get it running.
Converting the DeLorean to a carb isn’t as simple as just bolting the manifold in, as I will need to replace the rest of the fuel system to suit. This includes replacing a lot of components I have already bought new, such as the fuel pump and filter, as well as discarding a lot of other items I have already purchased, such as the injection lines.
Having said that, I didn’t want to miss out on the carb, as there may come a point down the line where I wished I’d bought it, and as I’ve mentioned they are rare as hell. so my plan is to keep going with the K-jet at this stage and keep the carb as a ‘last resort’ option. I figure I’ll keep working with Mark, make 1 more big order from DMC to replace the parts we have proven faulty, then if I’m still no closer to getting the car running, start looking at the carb option.
I’m determined to get this car drivable by the end of 2017. Not finished, but at least able to drive and perhaps even road legal.