ok i replaced plugs, wires, cut the cat off and welded on a straight pipe, changed the fuel filter, and none of this helped even the tinyest bit on my stumbling all thru the rpm range in every gear under load. I've narrowed it down to

1) Sending in my injectors to be ultrasonically cleaned and blueprinted. (i can only find 2 injectors where the hell are the other 2?)

2) Replacing the fuel pump. can some one point me in the direction of a good one under $200.

which fix do you think will work because i dont have enough to do both right now and this is my daily driver so i need it working correctly asap.

 

by the way its a 87 GXL with 110,000 miles and it runs good besides this ****.

 

1. the other two are under the intake manifold. Gotta remove the upper manifold to get at the primary injectors.

2. Gotta check fuel pressure before doing something this drastic.

Timing?

PaulC

 

im no mechanic so can you tell me how to check the fuel pressure? and is there anything different in checking/changing the timing on a rotary than a piston engine?

 

You need some fuel injection hose, and a fuel pressure guage. Remove the inlet hose from the fuel line spider (trace the fuel line up from the fuel filter, to where it connects to the metal line on the drivers side of the engine. Hook that line to the pressure guage, and the other side of the guage to the metal line (essentally you're putting the guage in the hose.

Fuel pressure should be approximately 28psi, 39psi with no vacuum at the fuel pressure regulator (according to my FSM)

Timing is pretty much checked the same way as a boinger.

I assume you have a chilton's manual, if not, go buy one, it outlines the correct procedures. Alternately you can download the FSM from fc3s.org, but that's a long download, and a lot of info to read through.

PaulC
PaulC

 

Don't discourage the man! The FSM is absolutely the best resource you can use to maintain, repair and modify these cars. I can't believe there are FC owners out there who know about these free online FSM's and haven't taken advantage of it.

To measure fuel pressure, you need to tee the gauge into the line with a brass tee fitting, like this:



Pic courtesy of the FSM...

 

any other tips?

 

You might also replace the pulsation dampeners. They have a huge impact if broken or not working properly.

 

is this a big job to change? how much do they usually go for?

 

1. Follow the advice from above.
2. Get the injectors cleaned.
3. Replace the fuel filter.
4. Clean the filter at the fuel pump i.e. in the tank.
5. Make sure there is a orifice in the vac line to the boost/pressure sensor.
6. Check with a digital ohm meter for a resistance of .2 ohms or less at the brown/black (could be a pure black wire on later 87's)wire on the boost/pressure sensor. If more than one ohm, run another ground(splice it in to the brown/black wire.
7. Check each fuel injector connector for frayed wires and sockets that might be pushed back.
8. Check the ground wires on top of the rotor housings for a good connection. They are in a circular connector, towards the aft end of the engine. Can't miss them.
9. Check each ground wire at the ECU for a good ground less than .2 ohms.
10. Be sure to install new orings on the fuel injectors and brand new grommets on the top and bottom of the injectors.
11. Check the timing to be per the fsm.
12. I have distaste for the *B/P* the fuel injectors phrase. The sucker will probably just ultrasonic clean them. B/P is just BS. Thats all he's gonna do. Personal predjudice. small humor.
13. Set the tps to read one volt while the engine is idling. All items connected up, just shove a digital meter positive lead up the rear of the green red wire on the tps connector, and adjust the tps screw till you read one volt. Done. Fully hot engine please.

5.