Thread: wont start!

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coolant sensor is located next to the inlet on the manifold and the gauge sending unit is in the head? two wire deal? is it worth replacing before I check cam to crank timing?

Denny--about the flooding---he had disconnected the fuel supply earlier

These symphoms are those of an engine with the cam timed wrong

What does it have for cranking compression? If any

Originally Posted by DennyW

Side note: Have you checked the TPS for proper settings ? And make sure you have your 5 volt reference available there.

no I have not! Could you explain what it is that I should be looking for?

those temp sensors for the computor have a standard ohm reading /temperature--if you have a manual it is probably listed in a chart
Check the compression numbers---if they are way low it will probably indicate you need to look at cam timing

the tps has three wires --a 5 volt wire, a ground wire and the return to ecm wire---the voltage out will vary from less than 1 volt to near 5 volts depending on throttle opening

the dealers used to disconnect the 9th injector on those early tpi cars because they would be flooded total by the time the driver had unloaded them, the jockies moving them around the lot,etc

too bad this forum doesn't have a chat thread so we could stay live, instead of sending the pidgeons back and forth

i burn them off with oxy/acet. because at least I can make it fire when I want to!
1989 GMC K2500

Chris here is the temp/ohms of the temp sensors
212 177
176 332
104 1459
50 5670
32 9420

Denny And Jerry,
After dinner I am going to give it another go around. First pull the plugs and clean them. shot of oil and cranking compression check. I found the area in the manual about testing the TPS and the CTS so I plan on that as well. With this info I may be able to find out something! I shall keep you posted. Thanks for the extra efforts!

well the tps is not functioning correctly. I have a good input of 4.99VDC and a good ground. Backprobing gives me an initial reading back to the ECM of 0.2 instead of the listed 0.6. While opening the throttle the TPS signal back to the ECM is not responsive, it doesn't change from the 0.2 reading.

The CTS gave a resistance reading of 1350 ohms at about 50 degrees ambient temp. This is far from the 5670 ohms listed in the manual.

Also the compression check gives a reading of 100 psi. This is on a cold motor with rings that have not been seated yet. I did give it a shot of oil before testing. This reading seems low to me but I have never checked a motor before the rings have been seated. My engine build stats are posted previously........ Could this be an indication as to mistimed cam? The pushrods have been adjusted carefully to assure that the valves are not hanging open.

Replace CTS and TPS? Any thought on the comp test?

Originally Posted by DennyW

Yes. It takes min 90 lbs just to fire the fuel.

The reading on the TPS sounds like you need to trace wiring, and check the TPS direct using a Good ohm meter. Slowly sweep it, and watch it for any drops, or fluctuations. If so, change it.

Direct test of TPS:

input lead to signal out lead gave no fluctuation
input to ground went from 1080 to 820
signal out to ground went 760 to 1346

denny do you agree on replacing both the TPS and CTS? Going ahead and verifying the cam timing........

to clarify.......you are saying to test the TPS signals in and out while cranking? The resistance tests were kinda weird too.

Originally Posted by DennyW

Read through here, and this will give you what I mean. This can be done at any point you want to check. Ground side included.

http://www.excelauto.com/online/Tech.d/strvdt.html

thanks. battery is charging now so will get at it tomorrow.
Any ideas on how to verify cam timing on assembled motor(water pump on).
I have a moroso wheel with a pattern for the balancer. Maybe I could pull the fan and space the wheel out to clear? I have a crank tool I made out of a balancer puller that I could turn it with.........