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97 850 Strange start situation. Runs fine, takes 12 cranks to get running.

Thanks for the info. I will get a license plate and insurance card here shortly. And drive to go pull old codes.

I am seriously suspecting the ECT coolant sensor, due to perfect starting and running, due to seriously green corrosion on it. And unplugging the connector to bad green corrosion. If it is a two-wire setup, shouldn't a jumper wire on and off the two wires simulate an open or closed circuit? Just trying to do simple troubleshooting before codes and parts. More research online and stage 0 work ongoing...

Update. I found the cooling fan engaged with the jumper wire. It works. Hahahaha
 
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Replaced the corroded terminals. I would just snip a replacement connector off a junkyard car with at least several inches of wire. You can also get replacement terminals, connectors, or a "loaded connector" that already has the terminals crimped and a wiring pigtail. This is your best bet for a professional level repair.


I would first look at scan tool data on the ECT. You could jumper them and watch the ECT voltage on the scan tool go to 5v, but all that would tell you is that the rest of the circuit is good, which it probably is.

A corroded ECT might not throw a code. Especially on an old 1997 vehicle. On a new car, it probably would throw a signal plausibility code.

Ask in the wanted section for a replacement connector. I'm going to the JY right now. I will see if I can snip one off for you.
 
The source for connectors and wiring is Dave Barton. I just recently bought the speed sensor connector loaded with wiring and contacts ready to be spliced in.
 
Sure! grab any easy relays, that 103 coded one in the fuse box (fuel pressure I think)
, etc. cam sensor, anything. They are probably give-away parts, and handy to have for diagnostics in a pinch.


Strange luck? It fired right up this afternoon.. First try. I will get the license plate, inspection tomorrow. Start working on completing stage 0. And finish polishing it. Four doors and that massive roof remains. Elbow grease. Tiring! Then, snap some pictures.
 
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Where is the ECT sensor on this engine? I saw some 850's but didn't see the ECT sensor easily.

Another issue on the whiteblocks is lack of compression on startup. It could be sticky valves. It can't hurt to do a fast compression test when the issue is present.
 
A fuel induction service (aka seafoam treatment) can help remove some of the carbon on the valve stems that may be causing them to stick open on a cold start.
 
Any ideas to host a picture i just took? Do I have to upload it somewhere? I found a 5 inch blue vacuum hose from the rear of the air box lid unconnected. No loose hose or connector nearby. Obviously, a missing hose or cut.
 
https://imgur.com/a/H8FB8IJ
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Thanks! Here it is. A mystery vacuum hose. Two come out of the bac of the air filter lid. The upper one is hanging loose
 
That's just a fresh clean air supply for some solenoid valve. 850 people can chime in. Or look for a vacuum diagram. Is there one under the hood?
 
I found diagrams, but none show lines from the air filter lid.A Robert DIY video shows it in a video clip to control the hot, cold preheater intake temperature flap. Interesting.
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And after I found that nipple with no hose, I found an 8" loose micro sized hose, smaller than any others. Laying loose iner there. Too small for this application. I have no idea where it came from. Hahahaha

But, I did find out why the R.H. headlamp fuse was blowing. A contructive electrical tape job inside the headlamp bulb housing. With both bare wires taped together. Amazing engineering. Scary. One step at a time. Only a cold start problem and two vacuum hose lines.

However, I did discover that there are more vacuum lines than the diagram shows.

Also as an update. I found a post about that relay 103 under the use box cover. It says to jumper wire pins #15 and 87 to troubleshoot if the relay could be fault. Trying that in the a.m.
 
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That's just it Zach. These have the ECT right in the t-stat housing, and the wiring corrodes right at the sensor body, usually nothing left to splice onto.
 
Quick update. I accidentally left the key ignition on for 30 minutes. Morning cold start, fired right up! Hahahaha

Scratching my head, but all systems are operational. Maybe time for maintenance to stage 0 now and newer than a 23 year old fuel system, relays, cleaning up the old girl. After that, a right front suspension clunk, chattering cv boot, motor mounts, and anything old and made of rubber or plastic. The usual.
 
I have seen coolant temperature sensors leak coolant into the wiring and make it all the way to the engine control module and corrode terminals at the ECM. I have also seen oil pressure sensors shoot oil thru the wires internally.

Anyways, I still recommend replacing that connector with a fresh "loaded connector". I will look again for you this weekend and see if I can snip one off for you.
 
Definitel found the issue now. I use a jumper wire and it fired right up, just fine. Alwas runs good once warm. Just this failed 103 relay. Here is a picture of the location, jumper wire, and relay 103.

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There are two sets of pin numbers for different year models. Best method for the jumper wire, Nose and tail ( window and ront bumper orientation) of the car pins. Not left or right. You will hear the fuel pump run consistently, and mine started right up.
 
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