I've got the same problem now, so if anybody figures this out...please post it.

 

I have the same problem with my 88 turbo. I have started 2 new posts concerning this pRoblem but so far no one has given me a solid solution to this problem.

 

If anyone is still following this post, I finally figured out my random no start. At the connector for the temp sensor, the insulation had worn off and the bare wires could touch each other thus causing a short. You have to pull back the outer wire cover to see it. I cut the wires and installed a new plug. So far the car has been starting perfectly for about 2 months and hasn't done it once. Plus my gas mileage has improved to 21mpg around town!! Hope this helps.

 

Thanks. I'll check that out.

 

My hot start troubles (never had cold start problems) were cured 100% certainly with new FPR. My fuel pressure was way high (pegged my 100psi guage) and fuel pressure leaked down very quickly with the bad FPR. Fuel pump also groaned loudly. All is normal now.

So I would definitley measure fuel pressure and leak down.

 

Manning, I have a NEW 2.5 bar Fuel Reg. if you want to try it... When I first bought my car, the PO just put it on but then I upgraded chips/MBC and fuel reg, so no need for it. You can at least try to rule it out some.

 

I had a similar problem today!! I drove the car for about 30 min. and then it started idling around 500RPM. I checked the temperature gauge and yup, it was at maximum. I kept driving thinking 65 MPH would help cool her down. It wasn't! I drove over to a friends house to say a quick hi and then go back to my car and she won't turn over. It wouldn't even attempt to turn over, all I could hear was a "zzzzzzz" which I'm guessing was the fuel pump. I had someone push me so I could pop the clutch. Started right up with idling problem. I drove home and put her in the garage. I tried fixing the idle, no use. Turned it off then tried to start it again....."zzzzzzzzzz" no attempt to turn over. I let the car sit for about 45 min. then tried starting it again. Started the first try. Was idling normal for about 30 seconds then started revving itself. The kept going back and forth from 500 RPM to 1500 RPM...THIS CAR HAS A MIND OF ITS OWN!!!??? PLEASE HELP ME!

 

So, what is it, like 9 months later and I have an update. Believe it or not I have no clue what the problem was, but it has not happened a single time this year. Not once. I started driving the car again after its winter nap a month ago and have not had a recurrence of the hot start issue. Knock on wood.

 

I had the same problem and after exhaustive research on the forums the top three candidates were
1. DME relay
2. Ref sensors
3. Fuel pump regulator

Distant 4th coil and misc...

I replaced items 1, 3, 4 and have not had a problem since.

Phil

 

I'm not sure if I've fixed mine 100%, but I've not had a problem since I replaced my fuel check valve, fuel filter, and FPR last week.

When I went to put a fuel pressure gauge on the car...I had no presure at the rail. That was a pretty easy test. In addition to that, the gas I poured out of the old filter had a dark greyish black tinge to it.

I've only driven the car a couple times since I changed everything since the weather has been great for my bike.

Next up is to replace all the sensor connectors on the wireing harness to make sure I'm not getting any shorts in them. I'll chime in here again if the problem comes back before replacing the sensor plugs.

Oh yeah, I changed plugs, wires, coil, dme relay, ref sensors, dme temp sensor, and the tps and still had intermittent problems.

 

I've been driving mine daily for the past few weeks because I've got the Civic off the road and my wife has been traveling and has the TDI. Not a single hot start issue. I'm a utterly baffled. And the thing is I haven't replaced anything since the problem first showed up. The only thing I did was disconnect and reconnect the vacuum line on the back of the FPR. And I am pretty sure it was holding a vacuum because it hissed when I disconnected.

 

This seems to solve any start issues I've had.

Good luck.

 

^^^ That's exactly why I'm replacing the connectors. I don't feel like poping the hood and wiggling wires when I want to start my car.

 

So I think I found my problem for this one. The hose for the vapor purge system has been disconnected for who knows how long.

https://rennlist.com/forums/924-931-944-951-968-forum/286933-how-important-is-this-line.html

 

Andrew,
I'm late to this thread so this may not be useful. You mentioned that, when you disconnect the vacuum to the FPR, you hear air hissing. You (?) compared the sound to disconnecting the brake booster.

There are two vacuum "circuits" in the 944. The power assist circuit uses vacuum to apply force in parts like the brake booster and the heater valve. This line has a check line and a reservior. In a perfect world, it maintains a fairly high, fairly constant vacuum level so braking force stays constant.

The second circuit is used to compensate for engine load. This one goes to the fuel pressure regulators and the "load sense" cannister purge control. This line needs to track instantaneous manifold vacuum so it does not have a check valve and overall volume is kept low.

It sounds like someone had connected your FPR to the assist circuit. Without compensation, any start attempted before the vacuum bleeds down will be lean. If you compensate with and adjustable FPR, then you would see ultra-high pressures with the vacuum line removed.

Hope this helps,
Bill