This is a MAP system that is in a 1937 chevy. Ran great for a number of years, but after sitting this year has become very hard to start. I have done the following.

1. Drained old fuel and added new fuel.
2. Replaced the plugs, the old plugs were black indicating I would imagine running rich.
3. Checked the fuel pump to make sure it is getting juice on prime and also immediately when cranking. Thought perhaps it was a bad fuel relay.
4. Checked the resistance in all injectors and all were in spec.
5. Hooked up a fuel pressure gauge and found the following.
a. When the key is first turned on it gives 40 psi.
b. With the pressure regulator without any vacuum it goes to about 50psi when idling.
c. With the pressure regulator having vacuum the gauge shows around 37 psi while idling.
d. The moment the car is shut off the fuel pressure drops off almost immediately.


I would assume the problem then is drop in fuel pressure.
a. I have pulled the vacuum hose off the pressure regulator to see if any gas came out. None, although when i did suck on the end there was a bit of gas smell, but the vacuum seemed to hold indicating the pressure regulator was ok. Also when it was idling and the vacuum was disconnected from the pressure regulator and then hooked up the pressure dropped from around 50 to 35 psi at idle.

b. Is there any test for injector leak?
c. Could it be a check valve in the fuel pump leaking? The pump is about 2 years old and is a delco.

Any suggestions on how to proceed further would be appreciated.

 

How do the spark plugs look after the car has set for just a few minutes. Wet? Smell like gas?


I would:

1. install fuel pressure guage.
2. without turning on the car (with key), power up the fuel pump. (note pressure)
3. unhook power to fuel pump. (watch pressure)

Most likely to be a leaking injector. Without power (pulse) from the ecm, all injectors should be closed.

Hope this helps!

 

It doesn't sound like a fuel problem if you've checked the system.

Things that go wrong when you leave your car in storage and it won't start:

1. Try checking the battery.
a. If it's been sitting too long, it may have desulfated and require replacement.
b. Then check the ground of the battery,corrosion may have set in on the terminals from the battery to where you grounded it-ie. Alternator bracket, air pump bracket or block.

2. Ignition module.
a. If the dialectric grease has dried out under the ignition module, the car won't start. Regrease the bottom of the ignition module with dialectric grease (or try vaseline-for some reason every Hayes manual says put dialectric grease or petroleum jelly ie. Vaseline on the terminals of batteries).
That's the cheap solution.
b. Check the leads on the ignition module with a voltmeter or ohmeter if that does'nt work, because your ignition module may have died.

3. Starter
a. Just take it to some autoparts store that will check it for free.

 

Sorry I was not clearer
1. Car cranks over fine.
2. You just have to crank it for about 2 minutes for it to start to fire
3. When it starts there is a lot of whiteshish smoke, smelling like gas.

I am now assuming that the car has been sitting for a year, that an injector is open and bleeding down.


If it was the check valve in the fuel pump, then when i crank it over it still shows 40 psi, and should start ok. When the plugs were removed and replaced the old plugs were black.

This points me to bad injectors, probably gummed up as this car is only driven in summer, and has been sitting for a couple of years, as last summer could not get it to run start properly.

 

bad coolant temp sensor on the front lip of the intake? When they go bad they tell the ecm that its like -40*c which will cause the same symptoms

 

Yeah my Iroc has the same problem at start up.