Odd no start issue - 83 SC Cabriolet

[mhackney]

I drive my 83 Cab 1600 miles/month during the driving season (primarily 2 trips to/from Rochester, NY from Boston, MA). She has been very reliable and I keep up on maintenance.

I returned home on Thursday evening in a torrential downpour for 6 hrs. I've driven in rain like this with no problems this summer. When I got home I decided to leave the car outside overnight so it would dry out in the sun. It was warm and nice here in Boston yesterday but I did not drive. This morning I got in and she started right up on first click like usual. The inside of the car had a fair amount of condensation on the windows so I put the top down to help dry out I drove 3 miles to the post office. At the end of my street (~1/2 mile) I stopped at the sign and noticed the car filing at about 1400RPM. This was odd enough that I noted it and I mention it here because this was unusual - normal idle when I reach that sign is 950 RPM.

I went to the post office and when I came out 3 minutes later she fired up but idled low and rough and stalled. And that's where the problem begins. No amount of cranking started it up. I suspected the fuel pump but couldn't really do much to diagnose. My friend from these boards Chris came to help bail me out. When he arrived (30 minutes later) I attempted to start the car and it fired up weakly and then died. It would just crank without starting. So I called AAA and got the car home.

We measured the voltage at the fuel pump fuse and that was good. I jumped the fuel pump relay pins 30 and 87a so the fuel pump should energize when the key is turned to accessory. When I turned the key to acc. I didn't hear the fuel pump turn on and I am *pretty sure* that I've heard the fuel pump under normal starting conditions.

So we put the car on the lift and removed the pan. We pulled back the + boot and hooked up a voltmeter and turned the key to acc. again. This time we heard the fuel pump run and saw V on the meter. I then hit start and the car fired right up. Turned off, put the relay back in and she fired up again. It was late and cold so we packed it in for the night and now I'm reading and researching to see how to diagnose and figure out what's going on.

Tomorrow I'll put the pan back on and reinstall the jumper and listen to "calibrate" my ear to a working fuel pump. Then replace with the relay and do the same. Once that's done, I'll go for a short 3 mile drive and park in my driveway to simulate today's drive.

I hope I can find a problem, it's tough to live with an intermittent problem driving so far from home as often as I do. Any debugging suggestions or diagnostics greatly appreciated

[wayne robson]

Hi mhackney, check my forum back on 11-06--15.Movie night gone bad, starter from pstallo
page 13 now, item no #8,may also help you,
sorry i am not good on computor,so dont know how to paste it,regards.

[mhackney]

Thanks Wayne. I forgot to mention that the first thing I did was check the engine bay and removed the distributor cap and rotor. It was dry as a bone - and the car had started up perfectly just 15 minutes earlier to start the trip, it was dry, sunny and 50ish today.

The other thing I forgot to mention is that Chris brought his fuel pressure check gauge over and we connected that prior to poking on the fuel pump. First thing to note: when I removed the fuel line to install the gauge, there was no fuel leaking out - the system seemed not to have any fuel pressure. When I then cranked the engine to start, there was no pressure measured - indicating the pump was not running.

I was suspicious about the rain and the fact that I left the car outside afterwards - something I never do - but the car started right up on first try after sitting.

[Pstallo]

Could the ignition coil be bad?

[stlrj]

My fuel pump acted up like that, sometimes working and sometimes not, when on it's way out. Finally it just stopped and it would not start at all no matter how log I cranked. Pulled the pan, tapped on the pump with the key on and it would make some weird noise but it did start...that's how I knew. Replaced the pump...done.

Hope this helps,

Joe

[mhackney]

Thanks guys. The ignition coil is 2 years old so I didn't suspect it. The behavior that we saw no fuel pressure after connecting the meter seems to be a strong indication that the fuel pump wasn't running. The fuel pump is located in a bad place to do roadside service on! I don't want to get stuck in Rochester with no easy way to repair. I also don't want to just start throwing new parts at it without really knowing the root cause. If these fail with intermittent behavior initially, that makes it tough to figure out!

[mhackney]

Got things back together and it starts right up. With the relay jumper in place the sound of the pump is very obvious. It is pretty noisy compared the pump in my ex-70 S. The pump is at least 10 years old. The terminals look clean and the + term needed a bit of tightening. I couldn't tighten the - term since the banjo fitting was positioned too close to get even a socket over it.

I took the car out on 2 short drives with a dozen stops and startups and all was well.

For the peace of mind, I'm going to replace the pump.

[boyt911sc]

Originally Posted by mhackney

Thanks guys. The ignition coil is 2 years old so I didn't suspect it. The behavior that we saw no fuel pressure after connecting the meter seems to be a strong indication that the fuel pump wasn't running. The fuel pump is located in a bad place to do roadside service on! I don't want to get stuck in Rochester with no easy way to repair. I also don't want to just start throwing new parts at it without really knowing the root cause. If these fail with intermittent behavior initially, that makes it tough to figure out!

Mhackney,

It is tough to troubleshoot an existing problem if it occurs at random. If you suspect the FP, bench test it cold and warm conditions. I have several fuel pumps that have been labeled as "NG" (no good). And I don't throw them out because sometimes they come back running (?) and would last for several months. But I don't use them in any of my cars and use them in my CIS bench tester or engine test stand which could I replace the FP easily and conveniently.

You should have a good working FP and keep a spare unit. A questionable FP could stop running anytime and could leave you stranded at any time and a place you do not want to be.

Tony

[Joe Bob]

I'll take the pump off your hands......I always wanted to tear into one.

[hawaii83cab]

Welcome to the 83 Cab club!!

[mhackney]

A little update...

This week I had to make a few short trips to the post office so I drove the 911 to see if I could get it to fail again. It did once and I looked for the jumper for the relay to test if the fuel pump was running (which I forgot to bring! doh!) I tried to start it again several times and it fired up on the 3rd attempt. I estimate that I had attempted startups maybe 9 times since the first failure and saw this one additional one.

Today I replaced the fuel pump. Took all of 30 minutes! It fired right up and I could tell almost immediately that “something was different” and better. For the last few months I’ve had a strange issue when starting from 1st gear that it almost felt like the clutch was grabbing (bucking) unless I gave it a little more gas. I suspect this was an early warning. This hasn’t happened at all today whereas it did yesterday on my last drive before replacing the pump. The car is also noticeably quiter and seems a little faster to respond to the gas pedal. I’ve been driving it for lots (12) of short trips today with no problems. I’ll do the same tomorrow and then it’s off to Rochester on Sunday. I feel cautiously confident that this was the issue.

The old pump was a Bosch made in Germany pump. I think I'm going to hang on to it and see if I can get it rebuilt as a spare since I've read that the new Bosch pumps are less reliable. Mine was made in Czechoslovakia.

[mhackney]

Have you joined the 83 Cab Registry I put together earlier this year? See my signature for the URL.

Originally Posted by hawaii83cab

Welcome to the 83 Cab club!!

[mhackney]

Well, I declare victory! I drove from Boston to Elmira NY yesterday. Then got up in 15 deg F this morning and drove from Elmira to Rochester. Lots of starts/stops and no problems with the fuel pump. Starts on first crank every time. Now I need to get some heat, 15 deg was coooollllldddd.