Hello,
Im Tullio Candidori from Italy,
i have the 1990 Blazer, I replaced the engine, with a new one, rebuilding. My truck have also the LPG system and The engine have the problem that I'm going to explain to you when it goes with the petrol( consequently also to LPG): with the cold engine the timing is ok(I adjusted it, according to the instructions) as the engine warms up, the timing goes late, instead of going early and the engine pops.In pratice more the engine warm up, more it goes late. I don't know what to do it. I changed and put news the MAP, the knock detonation sensor, the ESCM Electronic Spark Control Module, nothing the timing go out of adjust.I forgot, the check engine light never comes on(the warning light came on twice in error when my car go to petrol error ESC but then it went out by itself.
We checked the connections between all the sensors and the control unit and they are all communicating.I was missing the last sensor and Now I'm ordering from Rockauto the last sensor, the Engine Coolant Temperature Switch sensor the ECT(but now im waiting your advice before placing another order.......I think I've said it all.
I hope I was able to make the problem understood, for me as an Italian and I can't speak with the right technical terms, it is very difficult to explain everything.....and sorry for the writing errors that I made.
Please help me I'm desperate.
Thank You
Tullio Candidori

 

Hi,

The timing of the early fuel injected Blazers requires the basic setting to be made with the wire (usually brown) to the ECU being disconnected.
Should be located behind the carpet on the passenger side and has a small single connector. Else it will be off by about 8 degrees.

If you need more help PM me also in Italian.

 

Hi
for to set the timing I have always respected the procedure you told me! the problem is that the timing go out of adjust yourself. Maybe I couldn't explain well. more the temperature increases, more the timing is delayed. Thank You

 

When setting the timing do you have the clamp which holds the distributor in place loosened "just so" that it is hard to turn the distributor or do you loosen the nut 1 or 2 turns?
Common thing, when the distributor is loosened too much, by tightening after adjustment you push it down on a helicoidal gear which turns the innards and messes up the advance.

I do it this way:
Engine off, loosen the distributor clamp just so little that you can just barely turn the distributor. Then I leave the wrench on the nut in such a way that I can loosen a bit or tighten it during the setting.

 

Hello
I cant answer you in private message, do you have FB.
Ciao Error_401

 

Scrivi pure in Italiano qui nel forum, nessun problema.

 

Ciao Marco grazie per la tua disponibilitā e pazienza, abbiamo giā fatto tutte le prove che tu hai detto, ma siamo giunti al sensore ECT e' rimasto solo quello da cambiare e la centralina, li ho cambiati tutti, come ho messo sul post. Nelle Pagine di FB dove ho anche messo il post, quasi tutti mi hanno risposto che il problema dovrebbe essere sicuramente l'ECT, perchč questo sensore a secondo della temperatura rilevata fā regolare automaticamente la fase(timing)molti di loro mi hanno detto che proprio questo sensore ha dato molti problemi ai K5 di quell'anno...poi chissā dov'e' la veritā, di certo in Italia nessuno purtroppo č riuscito ad aiutarmi!! Ora l'ho ordinato su Rockauto e dovrebbe arrivare in settimana!! Sono esausto č da fine anni 90 che ho auto americane 82 corvette 73 Pontiac TA 455 ed ora questo K5 del 90 che mi figlio ha fuso, ma nessuna delle altre mi ha fatto impazzire come questo K5. ti trovo su FB?? Grazie Mille ancora per la tua pazienza.
Saluti
Tullio

 

Ciao,
Allora buona fortuna e che sia proprio questo. E possibile che l'ECT possa causare cambiamenti. Consiglierei in ogni caso di controllare tutti i fili e misurarne la resistenza per essere certo che non ci sia un guasto. Anche misurare un po (non ricordo se sono voltaggio o reisistenza l'ECT) il valore di quello montato adesso e quello che ti arrivera.
No, non sono su FB.

Facci sapere che cosa succede una volta cambiato l'ECT.

P.S. prova a trovare da rockauto i libri di servizio e gli schematici elettrici. Sono disponibili su CD-ROM. Io per la mia ce li ho. Attento a prendere quelli originali, non i Hayes.

Ciao Marco

 

OP has checked and re-checked all suggestions and narrowed down to the ECT. New ECT ordered. we'll see if it cures the problems.

 

Id built a LPG system for my 95 S10 and it operated exactly the same on either petrol or LP. So there must be a defect in the control system.

And the LP system got exactly the same mileage, to the cent, on either fuel.