Installed a TBI unit over the weekend with the ulitmate TBI mods done. I used a JET AFPR along with it too. I screwed up the stocker when trying to make it adjustable. The cost of a new stocker was only slightly less than the JET so...

Anyway, After setting the FP is about 10psi at idle, with the car running and cold. I took it out of a drive. WooHoo!!! What a difference. Turbo-Link says that I'm running rich though.

So yesterday AM I go out to turn down the FP a little to try and get rid of this rich condition. Start the car up and the FP is at 12-12.25psi!!! Mind you the car is cold at this point. I crank it down all the way and could only get it down to 10.75-11psi. Took the car for a drive. Not quite as fun as Saturyda but still much better than stock. Turbo-Link still says I'm running rich. After I get back to the house I check the FP again. Now it's all the way down to 9.25psi.

Is this change in FP related strickly to the engine temps or what? Anyone else have this going on???

 

could be fuel temps, which are related to engine temps because are damn fuel lines are metal and run along the valvecover. try replacing with rubber/steel braided lines and see if the fuel pressures change so much.

 

o or... the little diaphram in the pod is rubber, though its reinforced with some sort of cloth or other fibers it could also still stretch a little more at warmer temps causing fuel pressure to drop.

 

OK I can see both of those having an effect.

Should I be sure that I'm up to operating temps before I set the FP then? I'm think the answer to this is yes.

 

ya

 

I have an Auto Meter in-dash fuel pressure gage on my TBI system and am running at 15psi. I have NEVER seen it vary from 15psi more than 0.1lb, if that. EVER. From -10 deg F to 70 deg F (yesterday) it is ALWAYS at 15psi.

EDIT:

IMO, you got something wrong there. Fuel pump about to break and/or something funky going on in your regulator and/or return line kinked/plugged and/or fuel filter(s) getting plugged.

Do some diag work to see what you can find.

[This message has been edited by FastBroker (edited April 10, 2001).]

 

I've replaced the fuel filter recently. Just over a week ago actually. No kinks in the lines anywhere. The FP was steady with the stock regulator. Now with the JET installed on my "ultimate" TBI it is doing weird things. This AM I started the car and it went straight to 14psi. By the time I got to work, 20+ mile drive, it was back down to 11.5psi. I think I must have something put together wrong or the spring and or diaphragm is bad. I used a Walker TBI rebuild/gasket kit when I put it back together. I'm going to get another one of these kits and get my original TBI back together and see what I get both with the stock FPR and the JET AFPR.

 

Something ain't right in boomtown. try and figure that one out as it's not gonne help driveability any.

 

OK took the blasted thing apart again tonight. I find the diaphram that came with the rebuild kit is quite a bit different than the stocker. I didn't measure it but I'd guess it's about 1/32 of an inch thicker. Also the stock diaphram has a small(5/16") round piece on the top that is spring loaded. The new piece has a piece about the same size that can swivel but does not have the spring. SOOOoooo, I'm guessing this is the problem. I'm going to try putting one of the old stock units back in tomorrow night and see if that fixes things.

Also found that the spring in the regulator(remember this TBI came from a truck) was about 3/8 of an inch longer than the 9C1 piece. So I put in the 9C1 spring.

The FP seems pretty steady now at 12psi. But when I shut the car off the gauge still shows 2psi. Even after I took the fuel lines off to change out the injector pod! Flaky gauge again I guess. So let's see subtract 2 from 12 and I get 10psi aat the lowest setting that the JET AFPR can give. That sounds about right now......

[This message has been edited by NotDadsW41 (edited April 10, 2001).]

 

OK an update:

I bought another rebuild kit and installed it on my first TBI. And then put it back on the car with the stock FPR. Car ran good. but not nearly as strong as with the AFPR setup.

Now looking at the FP guage I see 15psi. WT*?? I think this blasted Summit gauge is junk. This will make the third one that I've bought. One leaked and the other's threads stripped. Now this one is just junk. Time to spend money on an Autometer I guess.

Fastbroker, do you have a part number for your gauge? And maybe some pictures of the install both in car and under hood????

Also my problems seem to be related to the diaphram in the FPR. The ones from the rebuild kits were quite different from the stocker. I have actually gone back to a stock one, they seem much more durable, with the AFPR. Now I seem to be running lean at WOT from what I've read in the tech articles, since I have started with the AFPR turn to it's lowest setting. Just wish I could count on the gauge to give me a reading that was correct..... or even close for that matter.....

 

Not sure of the P/N but it's the Mechanical 2-5/8" Auto Meter Fuel Pressure gage that comes with the FP isolator so that the gage can be mounted inside the cab. Like $80-90, I think. No pix and it's in the Jeep, anyway, so most won't care. It's besides the other 6 AutoMeter gages. Who needs a clock, anyways???!!! There's one in the Sony.