Broken down near Pt. Reyes, CA - Page 2

DRACO A5OG · DRACO A5OG's Garage

Yes, it is a toggle, "ON OFF" only. So you can control the pump and not leave it on too long without the engine running.

No Schematics, I am a mere mortal

BRB

DRACO A5OG · DRACO A5OG's Garage

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autojack · 05-28-2016, 10:51 PM

Perfect, thanks Draco! So for a short test I can just jumper + fuse it and see if it runs. If so, the relay that should come in the mail this week will sort me out.

DRACO A5OG · DRACO A5OG's Garage

Pretty much

. Remember do not let it just sit and let the pump run too long with the engine off or you will burn it out.

Break a Leg Brother!

famoroso · 05-30-2016, 10:36 AM

I'll be home later this evening.

I can get you my spare relay tomorrow.

theiceman · 05-30-2016, 03:29 PM

sounds to me like cht sensor. if it is you will kick yourself as you could have used that paper clip to jumper it out and get you home.

let it cool over night if it starts the next morning and runs fine till it warms up jumper out the cht with a paperclip if it then runs fine you need a new one.

the early rev.used a single wire a d grounded through the head. the new ones have a second wire which is a dedicated ground.

autojack · 05-30-2016, 03:36 PM

Quote:

Originally Posted by theiceman

sounds to me like cht sensor. if it is you will kick yourself as you could have used that paper clip to jumper it out and get you home.

let it cool over night if it starts the next morning and runs fine till it warms up jumper out the cht with a paperclip if it then runs fine you need a new one.

the early rev.used a single wire a d grounded through the head. the new ones have a second wire which is a dedicated ground.

It has been sitting since Saturday. Just now it started briefly, then I turned it off. Now it won't start at all. I looked at the DME relay and don't see any suspicious solder joints, but I'm going to reflow them anyway and give it a try.

theiceman · 05-30-2016, 04:05 PM

turned it off after how long ?

autojack · 05-30-2016, 04:10 PM

Less than 30 seconds.

After reflowing the solder joints, it still doesn't start. So unless the relay failure is something mechanical, it's probably not the problem.

What else can I test?

theiceman · 05-30-2016, 04:11 PM

you may as well try and jumper out your cht it wont harm it.
look in the back on the left side. you will see 3 white connectors its the top one . see if you see two wires at one side of the connector and one at the other . on tbe side with two wires shove a paperclip in there and see if it will start
may take a while if it is the cht as it will have been running rich.

i tnink its worth a shot. other than that its dme relay or fuel pump

Steve@Rennsport · 05-30-2016, 04:15 PM

Personally, I would be testing for spark right now,.............

Put a good spark plug into #1's lead and hold it against ground while someone cranks the starter for you and see if you have a nice blue-white spark.

autojack · 05-30-2016, 06:41 PM

Quote:

Originally Posted by Steve@Rennsport

Personally, I would be testing for spark right now,.............

Put a good spark plug into #1's lead and hold it against ground while someone cranks the starter for you and see if you have a nice blue-white spark.

I hear you. I'll pick up a new plug and try it.

ischmitz · ischmitz's Garage

Quote:

Originally Posted by autojack

The car is home, no drama. Hopefully I can get it sorted out soon. After the initial stall, I was able to get it to run two more times for about 30 seconds before it quit. After that it would only crank and not start at all. This makes me suspect that it was running on residual fuel those two times, and now has none. I.E. it's the DME. Does that logic make sense? I'll try the jumper to see if I can get it to run in the garage.

Hit it with starter fluid or brake cleaner or similar. A healthy 3-second spray full blast into the snorkel of the air box. Then try to start it. This is the quickest way to segment this.

If it doesn't catch I'd look towards the flywheel sensors, especially the speed sensor.

If it catches you know you have spark and flywheel sensors and this could be a DME relay, or fuel pump related issue.

Then, to check the DME relay quickly remove the 35-pin connector from the DME and short pin 20 to pin 19 with a paper clip inside the DME connector. With that when you turn the ignition to ON the fuel pump should come on and you need to be able to hear it running. If not, either the DME relay or the fuse for the fuel pump or the pump are bad.

After that you can fabricate the DME relay jumper IF you determine the DME relay isn't working with the paper clip in the connector.

Good luck,
Ingo

autojack · 05-30-2016, 10:24 PM

Thanks Ingo, that sounds like an easy place to start. I have carb cleaner handy. I'll report back when I have a chance. The air filter at the snorkel doesn't filter the vapor too much?

ischmitz · ischmitz's Garage

This (brake cleaner into the snorkel) worked for me when I had to diagnose my failing fuel pump. Let us know what you find

DRACO A5OG · DRACO A5OG's Garage

It will work fine, it is the vapors that will ignite.

autojack · 05-31-2016, 09:50 AM

I just tried the car, and it fired right up. I let it run for 3+ minutes. Idle slowly lowered to about 900 rpm. Felt a little rough at that point but I think it has always been like that, and then fine once I drive away. I shut it off, then tried to start it again, and it wouldn't. So something is intermittent, but apparently not when the engine is absolutely cold.

bpu699 · 05-31-2016, 10:55 AM

Quote:

Originally Posted by autojack

I just tried the car, and it fired right up. I let it run for 3+ minutes. Idle slowly lowered to about 900 rpm. Felt a little rough at that point but I think it has always been like that, and then fine once I drive away. I shut it off, then tried to start it again, and it wouldn't. So something is intermittent, but apparently not when the engine is absolutely cold.

Try the fuel pump relay. Just take one of the other relays and swap it. If it runs, its an easy fix...

autojack · 05-31-2016, 11:01 AM

Quote:

Originally Posted by bpu699

Try the fuel pump relay. Just take one of the other relays and swap it. If it runs, its an easy fix...

As far as I can tell, this car does not have a fuel pump relay. The fuel pump has a fuse, which is fine. See Fuse Box Label for 1988 Carrera

DRACO A5OG · DRACO A5OG's Garage

Definitely starting to sound ref/speed sensor related. Check the ohms on those sensors.