97 Blazer Starting Problems

My son has a used 97 Blazer with a difficult to isolate starting problem. It will not start after it has been turned off after a few minutes (say, 5 or minutes). If you prime the throttle body with a very small amount of gas, it will start. Once started it will idle smoothly and run just fine at speed. No stalling or hesitation.

We tested the fuel pressure and it is at 50-52 lbs with key on ignition off and drifts slightly downwards to about 48 lbs then holds. Run pressure is about 48 lbs. Fuel filter has been replaced. No codes on the scanner and no check engine light. Was told that the 4.3 ltr engine has been giving poor gas mileage prior to the present problem.

Does anyone know if I am looking at a fuel delivery problem, i.e., fuel pump, pulsator, regulator, or some sort of a sensor feedback problem, such as a bad MAP, TPS or something like that? I did check the MAP sensor according to the Haynes manual and the readings I get are not what the manual says to expect. Instead of the voltage reading going up as engine vacuum decreases with rpm, the voltage is going down.

I once had another vehicle with a bad MAP sensor that prevented starting the engine.

Any ideas will be appreciated.

Check FUEL INJECTORS

Sounds like a leaking pressure regulator, leaky CPI Injection lines, or leaking internal fuel lines. I'll bet it hard starts in the morning or after a few minutes, smells awful after some idling. Mileage blows, I believe the running pressure for that Truck is 55lbs, Does the fuel pressure maintain after you shut the truck off? If this is the problem something in the intake plenium is dropping raw fuel down the intake. The sure sign for this is to pull the upper intake plenium. One side or both side will be washed out and appear gold in color. You looking at $400US for the CPI Assembly and $70US for the Nut kit(Internal Fuel Lines). Theres plenty of info on the net, do a search on Blazer, CPI injection. I said enough but I should mention if it is the Pressure Regulator Lindertech.com is the only place I know of to purchase a regulator without the CPI Assembly. Chevrolet says the Pressure regulator is an unserviceable part.

I just got done doing my 94 Blazer. New CPI Assembly and Internal Lines.

Hopes this helps.

I will go with Jethro, but I would look at the fuel pressure regulator, my dad, my friend and I all have a 97 Blazer/Jimmy and we all have had to replace our fuel pressure regulator

Dear Jethro:
I have a 1993 GMC Jimmy 4.3 Wseries...
And, it runs rich idles rough and starts hard...will take about 30sec cranking to fire-up...the hardest start GM motor I have ever had...
1. removed cleaned replaced the erg valve twice...
2. changed plugs and the 3 on one bank were green tinged? and the oil had about one qt. of gas in it...
3. then the heater core went out, unrelated...
this truck has only 130,000 and is a good vehicle but it really stinks while idling...and I remember in the past it really smelled like gun powder...
Please [email protected]

After its running if you shut it off and try it again right away does it start easy? and after 15 minutes does it start hard again? I would pull the upper intake plenium, if either side appears gold in color you have an internal fuel leak. If its the passenger side you have a leaky pressure regulator, if its on the drivers side you'll probably looking a leaky internal fuel lines.

Good luck,.

After its running if you shut it off and try it again right away does it start easy? and after 15 minutes does it start hard again? I would pull the upper intake plenium, if either side appears gold in color you have an internal fuel leak. If its the passenger side you have a leaky pressure regulator, if its on the drivers side you'll probably looking a leaky internal fuel lines.

Good luck,.

Wow, yes it does start easy after running and immediately fires...
But, if I go into a store and return in 15 min. it starts hard again...
To pull the upper intake plenium is that the top above the intake...is it bolted on or what? Is this a simple job or should I have a local general mechanic...do the work...if so how hard is it to replace leaky pressure regulator? and or leaky internal fuel lines...is this leaky connections or the lines themselves...where can I get parts and what price range am I looking at? Thanks again... :o)

Its not a hard job to do, it would take you about 4-5 hours or so, if you do a search on the internet for CPI assembly and chev blazer, you'll find pictures and info on doing the job. If you took it to a local mech then the labour is not the part that will hurt its the parts. GM says the CPI Assembly is unservicable, therfore if it goes they say to replace the whole thing. A new CPI Assembly will run around $350 US for new one, the internal fuel line kit is about $70 US. Now you could check out lindertech.com, they have all the parts for these injection systems. Also they can sell you just the pressure regulator if you find out thats all you need.