Ran fine yesterday, today won't start, fuel pump never stops running

[TankII]

Ok, I'm perplexed. The car ran perfectly yesterday (other than the A/C kicking out and not coming back - yest, it has a BRAND NEW compressor!), and this morning it won't start. The fuel pump keeps running, never stops like it has reached full pressure. The engine is spinning like a top too - normally I hear it chug on one cylinder before it starts.
I swapped the vacuum fuel pressure regulator when I replaced the injectors in the spring, so I swapped it back no change.

Ideas?

Dave R

'91, 258K miles, original fuel pump.

 

[luigisho]

codes? Does the starter spin? If no spark then I would check CCRM for fuel pump issue, DIS, and PCM. Wiring is always a possibility at this age but look for the control stuff first.

 

[TankII]

Check engine light stays solid on with the jumper in place. That's a first....
As I mentioned, spins like a top (when I crank).
DIS connections are still solid (thanks to RTV).
Have to get an assistant to check for spark. But, I don't smell fuel and it is in a shed and the plugs are bone dry.

 

[zoomlater]

I had an engine just spin (which sounds like what you are describing) due to a timing belt installed backward during a 60K. The timing must have been off enough so it never had chance to start the engine. Do you have an extra PCM to swap in

 

[TankII]

No, I don't have another PCM.
It was running fine and revving cleanly to 7k+ on my way home.
I haven't tried popping the timing cover off, but with the check engine light on solid, I'm not sure where to start - without a PCM.

 

[rubydist]

I think its most likely a pcm also. The pcm tells the fuel pump to run for a few seconds when you first turn it on, and if that continues, its either the pcm or the ccrm has a sticking relay. The other symptoms you have suggest pcm.

 

[luigisho]

If the check engine light is solid and codes can not be pulled then PCM or it's wiring is the first suspect. If it was just not running then I would throw timing belt slippage into the mix but electronic issues trump that. What is the RTV you speak of for the DIS module?

 

[TankII]

The ends of the DIS got beat up during various repairs over the years so the end covers are broken off where the retainer clips are. So I had to RTV the plugs into the sockets.
Front engine 60K was done about 10K ago (2017). Top-end including injectors and bearings was done about 1K ago *Not much driving recently). A/C was replaced in 2017, but the reman compressor blew and was replaced with a new one, along with dryer and sensors about a week ago. I only drove the car twice since then.

 

[luigisho]

I wonder about that DIS. Did you install the ac components? Underhood movement? Computer is my all things being equal best guess. DIS that is RTV'd together with alot of underhood ac work is second.

 

[luigisho]

You're jumping the right pins for CEL? https://web.archive.org/web/20041215140400/http://www.shophoenixproject.com/eec/eec.htm

 

[TankII]

I thought the contacts were messed up (using a paperclip in Feb worked fine) so I put two spade connectors on some 10ga wire and used dielectric grease. Still no change. Yes, I'm going from Ground to the top-left connector.
I've been using dielectric grease on every contact I disconnect for the past 8 years just to reduce any corrosion potential.

 

[NoSlo]

Not from the "ground" but rather you connect the VIP DLC self-test input (C199, single lead, brown, PCM48) to the signal return line (C198, gray/red signal return reference voltage, PCM46, top right pin when two pins are on top and four on the bottom).



The CCRM outputs a fuel pump monitor signal to the PCM19, but this is the same wire that powers the pump. The PCM should understand when the pump is running. The PCM doesn't know the pressure. If the pump stays on and you have rail pressure, fuel is eliminated even if KOEO acts weird.

Have you tried turning it off and on again? Disconnect the battery with headlights on for 10 minutes...

I guess you'll have to define what "spinning like a top" means. Easy spinning could be broken timing belt, giving little compression or timing belt resistance.

More than likely is something about the recent AC service, them pulling on wires putting in hoses, etc.

 

[TankII]

Couple of pics - the jumper and the DIS.

I didn't get the chance this morning to pull the battery, or check the timing belt. I'm on-call the next two weeks, so it will be a 50-60 hour week (x2)

 

[Tomuza64]

This just happened to me a couple of weeks ago but fan was running as well. replaced Ccrm and did not help. Replaced PCM... Fixed!

 

[FastCAD]

No, I don't have another PCM.
It was running fine and revving cleanly to 7k+ on my way home.
I haven't tried popping the timing cover off, but with the check engine light on solid, I'm not sure where to start - without a PCM.

My 2 cts.
I have owned my '91 for 27 yrs. In the early days I voluntarily bought up lots of "spares" because I already knew the nature of the SHO from "shotimes". The "original equipment" was still available at that time just"not cheap". That turned out to be enough to get me through the rest of the 20th century.
In the early 2000's I bought another '91 Just like the one I still had. This is where my point comes in.
When I had a suspected problem that I could not pin down I would take the "known good part" from one and installed it in the other. This saved a lot of time and money.
Since losing my backup SHO to a confrontation with a guardrail ( I lost) my best option.
I recently had a problem like you described but I had a "known good" PCM, problem solved.
I know that this is not a "cheap" option but in the end you can spend more "time and money" not to mention the aggravation, blood and foul language.
I still have my first '91 thanks to this method just like other members do because they like their Yamahammers.
My '91 still runs and performs very well and it is still my personal daily driver with some mods and 225,000+ on the clock and the heads have never been off.
I owe more than 2 cts. to this forum and I will be making my donation.

Best to ya

 

[luigisho]

Yes. Best practice is to have access to a known working CCRM and PCM for sure if you can afford it. These days throw in a crank sensor and maybe IAC/IAB. I'm not sure if those aftermarkets are working right looking at some of the posts this year.

 

[TankII]

Replaced the DIS, checked the harness. Going to try a PCM - if I can get the old one out. The factory screw isn't centered on the slot and I can't get a grip on it. I don't want to destroy the bracket or the screw.

 

[luigisho]

You talking about the little white one behind the glove box?

 

[TankII]

Yup. The metal clip wasn't centered with the screw, so half the screw is stuck in the slot. Only three sides are visible, and no way to grab two at a time because of the extreme angle of the screw head.

 

[luigisho]

I'm trying to remember if the slot terminates before the end of the clip or if if the slot extends all the way to the end. If it was an open slot all the way you might be able to physically pull the clip out toward you with the screw still in there. Then you could attack the screw without th ebracket in the way. I'm looking for a pic of it since my SHO is parked 45 min away. I bet Dan Barbush (SV&HOdan) has pulled enough over the years from his parts cars to know.