trouble starting 95 Blazer

My friend has a 95 Blazer with a 4.3L Vortec (same as my girls 95 Jimmy) and he's been having trouble starting the car.

He said it wont start unless he sprays some starting fluid into the intake. He said once it starts it runs fine. Now if it would have started and immediately died, I would have said fuel pump but since it runs after that I'm confused. He said it's like that every time he tries to start it. But once he sprays some starting fluid in the intake it fires right up and runs fine.

Any thoughts on what to check?

Thanks

tell him to stop using the starting fluid or he'll be changing the engine.
there is a sensor that tells the tb how much fuel to give when cold or a starting situation.
You will need added input on this as I dont know the name of the sensor.
Just tell him to stop the eather till it is figured out

Classic indication of a fuel delivery problem. Check fuel pressure and leakdown rate. Post your results and we can help you diagnose the problem.

gotcha, I will let him know to not use the starting fluid. Thanks

old_master,
thanks for the PM. I have the pressure gauge but not the other stuff, I will have to look into those further. Once I get a chance to get over there and do to the tests I will post back the results. Thanks

I was dealing with the same problem and recently found out it was the fuel regulator. it's not in a very friendly place, so i have to get it done and it will cost about 350.00 to do 100.00 for parts, the rest labor.

My friend has a 95 Blazer with a 4.3L Vortec (same as my girls 95 Jimmy) and he's been having trouble starting the car.

He said it wont start unless he sprays some starting fluid into the intake. He said once it starts it runs fine. Now if it would have started and immediately died, I would have said fuel pump but since it runs after that I'm confused. He said it's like that every time he tries to start it. But once he sprays some starting fluid in the intake it fires right up and runs fine.

Any thoughts on what to check?

Thanks
55/61 is specs on the 4.3 W code engine

It needs full fuel pressure around 60 lbs for the injectors to squirt fuel on cold engine cranking.
Even 2-3 or more lbs low will give you a hard start cold.

After started they will run and sometime start all day on lower pressure.

Always use just carb cleaner for starting a engine.
Starter fluid can blow a lot of stuff up or off.
MT

well, I finally got a chance to get over to my friends and check the fuel pressure.

The pressure went up to 40psi and after probably more than 5 minutes the pressure hadn't dropped past 36psi. So there isn't enough pressure but there isn't a leak since it held pressure fine.

old_master, in your PM you had mentioned putting a 5/16 shut off valve in the return line and to slowly shut it while jumpering the fuel pump to see if the pressure rises indicating the fuel pump is capable of producing enough pressure. Where should this shut off valve go exactly and where should I get the shut off valve from?

If the fuel pump does show it's capable of producing enough pressure, what else could be the culprit?

well, I finally got a chance to get over to my friends and check the fuel pressure.

The pressure went up to 40psi and after probably more than 5 minutes the pressure hadn't dropped past 36psi. So there isn't enough pressure but there isn't a leak since it held pressure fine.

old_master, in your PM you had mentioned putting a 5/16 shut off valve in the return line and to slowly shut it while jumpering the fuel pump to see if the pressure rises indicating the fuel pump is capable of producing enough pressure. Where should this shut off valve go exactly and where should I get the shut off valve from?

If the fuel pump does show it's capable of producing enough pressure, what else could be the culprit?

Did you try the fuel pressure regulator? It's about $44 from Advance or a used on from the boneyard just to see.

Leakdown is approximately 10%, which means the check valve in the pump is OK and there are no leaks in the regulator or fuel lines in the plenum. The most likely culprit is the fuel pump, although high resistance in the power circuit to the pump, or a poor ground for the pump could also be a problem.

The safest way to check pump output capability is to install a shut off valve in the return line. Usually there is a quick connect fitting somewhere between the intake manifold and the tank. The valve set, (5/16" & 3/8") usually runs around $400 but with parts readily available at the auto parts store and a good hardware store, you can make them both for less than $75. The valve temporarily installs inline at the quick connect fitting. With the pump running continuously, slowly turn the valve toward the off position while watching fuel pressure. It should reach 75psi. Do not allow the pressure to rise above 75psi or the fuel pressure regulator can/will be damaged. If pressure doesn't rise to 75psi, you need a new pump.

The easiest way to check pump output capability is to connect the fuel pressure gauge directly to the fuel line at the fuel filter, (not allowing fuel to the regulator, lines, or injector). Momentarily apply battery voltage to the pump, pressure should reach at least 75psi. If not, you need a new pump.

I'd send you a "How To" for building the gauges, but my external hard drive crashed and I can't get to it right now.

Did you try the fuel pressure regulator? It's about $44 from Advance or a used on from the boneyard just to see.

why would I do that when the pressure wasn't leaking?

Also, I just replaced the regulator on my girls 95 Jimmy within like 2 months ago and the regulator was $33 at autozone.

Believe me, I would have preferred it to be leaking from either the "nut kit" or the regulator but with it holding pressure I know it's not one of those. I think I would rather replace one of those than the fuel pump, I've done that twice on my girls Jimmy.

Leakdown is approximately 10%, which means the check valve in the pump is OK and there are no leaks in the regulator or fuel lines in the plenum. The most likely culprit is the fuel pump, although high resistance in the power circuit to the pump, or a poor ground for the pump could also be a problem.

The safest way to check pump output capability is to install a shut off valve in the return line. Usually there is a quick connect fitting somewhere between the intake manifold and the tank. The valve set, (5/16" & 3/8") usually runs around $400 but with parts readily available at the auto parts store and a good hardware store, you can make them both for less than $75. The valve temporarily installs inline at the quick connect fitting. With the pump running continuously, slowly turn the valve toward the off position while watching fuel pressure. It should reach 75psi. Do not allow the pressure to rise above 75psi or the fuel pressure regulator can/will be damaged. If pressure doesn't rise to 75psi, you need a new pump.

The easiest way to check pump output capability is to connect the fuel pressure gauge directly to the fuel line at the fuel filter, (not allowing fuel to the regulator, lines, or injector). Momentarily apply battery voltage to the pump, pressure should reach at least 75psi. If not, you need a new pump.

I'd send you a "How To" for building the gauges, but my external hard drive crashed and I can't get to it right now.

ah, ok. So if the pump output checks ok then I would look into the possible high resistance or poor ground?

Well, I definitely like the sound of the "safest" way depending on where the quick connect is located. Also, is the quick connect the ones you use the fuel line tools to separate? Sorry for lack of description, but if I'm thinking correctly I just bought a set of those for my SVT when I removed the fuel rail. Just making sure I know what I'll be needing.

Yes, if you could send me the "how-to" on building my own that would be great, 75 sounds a lot better than 400. Whenever you can get that to me would be great, no hurry.

Thanks

ah, ok. So if the pump output checks ok then I would look into the possible high resistance or poor ground?

Well, I definitely like the sound of the "safest" way depending on where the quick connect is located. Also, is the quick connect the ones you use the fuel line tools to separate? Sorry for lack of description, but if I'm thinking correctly I just bought a set of those for my SVT when I removed the fuel rail. Just making sure I know what I'll be needing.

Yes, if you could send me the "how-to" on building my own that would be great, 75 sounds a lot better than 400. Whenever you can get that to me would be great, no hurry.

Thanks


The pump must be supplied with good power and good ground before it CAN produce full pressure. The next step is to make sure the pump is getting it. The tests are made at the fuel pump connector: The pump must be getting battery voltage on the grey wire, (when the relay is activated). The black ground wire must be less than 5 ohms resistance to the chassis ground. If the pump is getting good power and ground, the pump is bad.

Yes, The quick connect fittings are the ones with plastic inserts and you can use the fuel line tool, (but it's not necessary if you know the trick).

If the fuel filter was plugged would it be posible to get a lower reading on the guage? I guess its unlikley but maybe wishfull thinking on my part...I changed the pump on my 95 a while back and It was doing the same thing as your friends....your probably better off to just change out the pump...

A restricted fuel filter or pressure line will affect fuel pressure at the test port. A restriction in the fuel return line would cause the system to over-pressureize. This is the reason a good visual inspection is important. Also, the filter is always checked/replaced BEFORE system diagnostics. If the system is properly diagnosed, the "guesswork" is removed and only the faulty part is replaced.

I will be sure to check for power and ground to the fuel pump.

Also, what is the proper way of inspecting the fuel filter?

If you replace the filter, you know it's good. If you want to check it, remove the fuel filter and drain the fuel from it. Locate the arrow that shows the direction of fuel flow. Blow through the filter. There will be very little resistance if the filter is clear.

If your fuel gauge is a quality one and is accurate then you definitely have a fuel pressure problem. These CPIs are very fuel pressure sensitive. They need a lot of pressure to start (around 60 psi).
Other things I found causing a hard or no start is the need for new spark plugs. The gap spec is .035" and mine wouldn't start when its cold out with a worn out gap of .060" to .068". Fresh tune-up and mine starts great.

no, the fuel filter hasn't been replaced. But I spoke with him yesterday about the fuel filter and he decided to just go ahead and replace it since it's a cheap part. Then we will recheck the pressure and go from there if we need to build the check valve and check if the fuel pump can build the pressure required.

If your fuel gauge is a quality one and is accurate then you definitely have a fuel pressure problem. These CPIs are very fuel pressure sensitive. They need a lot of pressure to start (around 60 psi).
Other things I found causing a hard or no start is the need for new spark plugs. The gap spec is .035" and mine wouldn't start when its cold out with a worn out gap of .060" to .068". Fresh tune-up and mine starts great.

yes, we know we have a fuel pressure issue, just trying to determine where exactly that problem is so we can fix it.

The spark plugs aren't the problem. Back in August we replaced his head gaskets and at that time also replaced the cap, rotor, wires and plugs. So those are fine. Thanks for the suggestion though.