1997 Blazer with fuel problems. The truck is 4x4 Ls 2door automatic. A very nice truck but has no power. It does not seem to misfire. No check engine light. Runs and idles smooth. If you press on the throttle past one eight pedal it bogs when in drive. The engine revs but goes nowhere and sounds like it is starving for fuel or air. If you let off and wait it will pull and get you to about thirty. It seems to rev good in park but if you rev it high it breaks up. So today I wanted to check the fuel pressure. I got a gauge from autozone but it does not bolt up to the line under the hood. It is for gm tbi.

My plan was to check the fuel pressure and then check the spyder injection. Is this sfi mpi cpi? Anyway I released the fuel pressure and to me it did not seem very high it did come out but not 60psi worth at least to me. It seemed to gurgle out a little bit. At this point I knew that I wanted to check the spyder injection system for leaks. It was gunky but it does not seem to leak. When you prime it one or two injectors squirt a little. Is this normal? With the coil unplugged I had someone turn the engine over and all the injectors squirt. My goal for tomorrow is to find a way to use my fuel pressure gauge on the truck. It shouldn't be a problem since I will have some daylight. If I knew the thread size of the schrader valve I could get an adapter. Thanks.

Just remembered that the fuel pressure regulator holds vaccum but it looks like there is supposed to be a vaccum line attached to it but there is nothing.

 

Has anyone else had a similar problem?

 

The search tool is a wonderful thing...

96 thru mid-02 are SCFI motors.

The pressure regulator is inside the plenum and is therefore subjected to manifold vacuum without requiring a vacuum hose.

The injectors should not leak.

Here are a few threads that may be of interest to you:
Fuel Pressure Gauge Adapter
96+ Fuel System Diagnosis

Many more are just a search away.

 

Just got the fuel pressure tester to hook up. She has 60psi. Did I mention that when you prime the pump that some of the injectors squirt a little fuel. This is with the key in the accessory position. The lines to the poppets do not seem to leak. The regulator seems to hold vacuum but will check again. If the mpi upgrade wasn't 300 I would just get it. I am going to pull the plugs and see what they look like. First I am going to read those write ups you sent. Thanks.

 

Hello Chris,

I am just going to throw this out to you. I have a 1997 also. I am not sure how many
miles you got on yours and what kind of parts you have changed or know what has
been changed. I had a similar issue with power back a year ago. Found out it was
my catalytic converter. It was plugged up. My car did not throw any codes.
It's worth checking. You can probably look through some of the posts and find a way
to check your catalytic converter. If it is OEM you should be able to unbolt it in a few spots
just to see if there is back pressure holding your power down. I was surprised that my oxygen sensors did not give me a code. I wound up changing my whole exhaust system.
4 New Oxygen sensors , Catalytic converter, Muffler and pipe. It all bolts together as long
as you get OEM replacement parts. I think it is worth a try/check. Good Luck.

Mark

 

You must have missed that part of my reply... If the injectors are leaking, you have a problem with the spider and it needs to be replaced.

What did the fuel pressure do once the pump shut down? That is also part of the fuel system diagnosis.

Leaking fuel injectors can cause harm to other things as well. One of those being the catalytic converter. An over rich condition on one or two cylinders may not be enough to influence the O2 sensors into leaning out the mixture especially if it is only one cylinder per bank. But that over rich condition definitely can affect the catalytic converter over time.

Start with getting the fuel system proper and move from there.

 

Yeah I did miss that. I guess the spider is bad. I pulled the plugs and they were wet and black on one side. Is there a way to move the steering shaft out of the way? Are autolite single platnums good? Autozone sells the mpi conversion for 300. Is this worth it? Will I need to do anything else to upgrade it? I can try disconnecting the exhaust before the cat to see how it runs. Thanks for that. The spider is probably no good from the sounds of what you guys have said so I will be looking for a replacement tomorrow. The truck has 152,000 on it. The spider was so dirty that I figured it was not working correctly.

 

Check with your local Chevy dealer. The MFI conversion PN has been posted before along with what else may need to be changed. You'll spend just as much on the stock SCFI spider, if not more.

Go with AC Delco double platinums just as were installed from the factory.

 

The pump makes 60psi but I did not see how it holds pressure. It is probably loosing pressure because of the injectors leaking but I will check. Thanks again.