Fanta Posted March 4, 2009 Report Share Posted March 4, 2009 Not me --- he car won't run right. I can drive it a little if I stay away from boost (though it's not totally right even then). It feels like it's missing a bit and won't build boost except maybe in 3rd or 4th gear at a decent speed and I jump on the throttle a bit (high enough on the RPMs where the load isn't too bad on the engine). No matter what the car/engine does, the fuel pressure does not change... When I have a pressure gauge hooked up to the TB, it stays at about 40psi no matter what the boost pressure or engine speed. I did get an universal fuel pressure regulator but haven't hooked it up yet. I was going to do that and rebuild the TB too (both items have been purchased though I'd need to get some things to hook up the regulator to the stock TB). I want to try one thing first though, I am going to remove the exhaust from the bottom of the downpipe (I started to see these issues when I put the exhaust from the parts car though it was hardly noticable when I first installed it). Maybe the parts car cat on the mid pipe is messed up (my old exhaust didn't have the cat on the mid pipe). I might try this tonight or tomorrow night. ---- Link to comment Share on other sites More sharing options...
jahjah Posted March 4, 2009 Report Share Posted March 4, 2009 who dis? Link to comment Share on other sites More sharing options...
jahjah Posted March 4, 2009 Report Share Posted March 4, 2009 my first guess is Timing or check the plugs. check your Rotor cap and all that. see if its something simple Link to comment Share on other sites More sharing options...
Jehu Posted March 4, 2009 Report Share Posted March 4, 2009 (edited) It's mine... I can't even remember what all I went through. I know I did compression test, timing is perfect, new wires, plugs and rotor cap/button, ISC reset... Current: http://www.starquestclub.com/forum/index.php?showtopic=81877 Previous (shows some more history and work done): http://www.starquestclub.com/forum/index.php?showtopic=81285 Post of stuff done/fixed/checked: http://www.starquestclub.com/forum/index.p...mp;#entry717850 Edited March 4, 2009 by Jehu Link to comment Share on other sites More sharing options...
mikec Posted March 5, 2009 Report Share Posted March 5, 2009 If the fuel pressure does not increase as boost pressure builds up you WILL kill the engine. Normal fuel pressure regulators have a "reference pressure" port - this is the one with the small vac hose. That vac hose connects to whatever pressure the tips of the fuel injectors see... on a StarQuest that means the throttle body. If the aftermarket FPR does not have a "reference pressure" port at all; it is a lousy match for a StarQuest. You'll never get the engine tuned right with such a FPR... at least not without spending lots of money on add-on computers and what-not; it would be far cheaper and easier to install the right type of FPR. Since it sounds like you have a pressure guage hooked up, try these two tests: * Engine OFF. * Run a beefy jumper wire from the battery + post to the one-wire test connector hanging from (or taped to) the wiring harness between the air filter canister and fender. That'll run the fuel pump. Test 1: * What's your fuel pressure? It should be around 36 to 38psi on a "stock" or stock-compatible FPR. Probably 40psi on your car based on your description. Test 2: * While everything is connected that way, use pliers to squeeze the fuel hose from the FPR back to the fuel tank (NOT the larger hose from the FPR to the throttle body inlet) until it's shut. What's the fuel pressure now? By doing this, you've basically disabled the FPR. On a working/good fuel pump, you should see at least 60psi "dead head" pressure. Don't leave the hose crimped long; this pressure stresses the fuel injectors and other hoses/connections a bit. If the pressure is still low, your fuel pump, fuel lines, or filters need attention. mike c. Link to comment Share on other sites More sharing options...
Jehu Posted March 5, 2009 Report Share Posted March 5, 2009 40psi w/ engine off and just the test port given power...and it does raise when pinched (actually went higher than 60 if I recall correctly). One thing to add/note, I remember hooking the stock fuel pressure regulator to the port that I use to hook in the blow off valve and the pressure did change (was like 32 at idle and I think went up with revs...I think). Maybe something blocking the normal port that the regulator is supposed to be hooked to? Link to comment Share on other sites More sharing options...
Jehu Posted March 6, 2009 Report Share Posted March 6, 2009 OK, idles and revs fine...just doesn't like boost. It seems the fuel pressure is trying to raise with the boost but I can't get it in boost well enough to really tell (plus the gauge I have goes up to 100 so the 1 psi increments come quick). Any ideas? Link to comment Share on other sites More sharing options...
BOHO Posted March 6, 2009 Report Share Posted March 6, 2009 not throwing any codes? Link to comment Share on other sites More sharing options...
Shelby Posted March 6, 2009 Report Share Posted March 6, 2009 blow off valve uses vacumm,,, fuel press reg uses boost NO VACUUM Link to comment Share on other sites More sharing options...
Jehu Posted March 6, 2009 Report Share Posted March 6, 2009 (edited) Right, I only used the port that would drive the blow off valve as a test to see if the stock fpr would change the fuel pressure and it does. The stock FPR is hooked to the correct port on the TB right below it right now. I haven't checked for codes lately. I'll try to check in the morning (my night is booked tonight)... But the car seems pretty drivable out of boost. Edited March 6, 2009 by Jehu Link to comment Share on other sites More sharing options...
Fanta Posted March 6, 2009 Author Report Share Posted March 6, 2009 only these cars are utter dogs without boost Link to comment Share on other sites More sharing options...
Jehu Posted March 6, 2009 Report Share Posted March 6, 2009 Mine seems ok...it's a 4 cylinder remember! I'm thinking of picking up a new coil...it's one of the only things I never replaced when I first was getting it running. Might be causing the boost to blow out the spark since the spark might be weak from a bad/old coil... Link to comment Share on other sites More sharing options...
Shelby Posted March 6, 2009 Report Share Posted March 6, 2009 sounds like a leaky bov Link to comment Share on other sites More sharing options...
Jehu Posted March 6, 2009 Report Share Posted March 6, 2009 (edited) The BOV is not hooked up right now...and I'd venture to say that all the black smoke coming out of the exhaust while it's boosting indicates that I'm not burning all the fuel being injected. A possibility to me is that the ECU sees boost but for some reason the engine doesn't (can't?) use/burn all the fuel the ECU gives. Edited March 6, 2009 by Jehu Link to comment Share on other sites More sharing options...
Jehu Posted March 13, 2009 Report Share Posted March 13, 2009 So, still having boosting issues. Rebuilding the TB didn't help in that dept (though I'm no longer spitting fuel from between the TB and the mixer!). Next step is to check the charge piping/system. I don't have an air compressor so the first step will be disassemble and inspection... What it does is it runs great out of boost, no matter the rpm. But once it hits 0psi or more (stock gauge), it will bog. If I can get the rpms up first, it almost seems like it wants to run right about 40-50 percent of the time but it's in and out kind of power. Any thoughts? Any help will probably help keep me from tossing it off a cliff! Link to comment Share on other sites More sharing options...
Couth'nize Posted March 13, 2009 Report Share Posted March 13, 2009 Did you make sure the solenoid valve next to the pressure sensor is good? I had similar problems and here is my solution. The old valve was dead ( I put 12v on it and it did not click).You can put your finger on the valve while the car is at idle to feel it click on/off every so often.My '86 ran like crap, kinda like what you discribe....so I decided to use the valve that was use for the emission control stuff. http://img27.imageshack.us/img27/8836/11258637.th.jpg http://img25.imageshack.us/img25/6207/dscf00801272096.th.jpg Now my car run like a champ. Link to comment Share on other sites More sharing options...
Jehu Posted March 14, 2009 Report Share Posted March 14, 2009 What is that other sensor originally used for? I think I've seen it bolted to the throttle body... Link to comment Share on other sites More sharing options...
Komeuppance Posted March 14, 2009 Report Share Posted March 14, 2009 That solenoid with the yellow dot was used for emissions, some have had success replacing the altitude sensor with it, I didn't... maybe both were busted. You should check the vac line setup in the FAQ's. The FPR is supposed to have it's vac line connected right before the throttle plate. You should also make sure your pressure sensor/boost sensor and altitude sensor/boost solenoid are connected properly to the correct vaccum port on the TB. After those steps have been taken, you now need to do a boost leak test on your entire system. -Robert Link to comment Share on other sites More sharing options...
Jehu Posted March 15, 2009 Report Share Posted March 15, 2009 The car ran normal/fine before and the vacumn lines were not changed but I will double check... Link to comment Share on other sites More sharing options...
Shelby Posted March 19, 2009 Report Share Posted March 19, 2009 what yr is the fuel system, if it has a MAP sesnor it must see full vac and boost ,if it does not see boost the 86and below ecu will not add fuel , by the same token all systems if theres an IC leak will over fuel the engine Link to comment Share on other sites More sharing options...
Jehu Posted March 19, 2009 Report Share Posted March 19, 2009 It's all 86... Link to comment Share on other sites More sharing options...
AlexNYC Posted March 20, 2009 Report Share Posted March 20, 2009 I just got into the same situation myself. I took the car for a drive on sunday, just for a stretch it was only 15 minutes. I was driving it like i had just stolen it. When back home park the car wait it a minute before turn it off. That was it. Today I got it started it warmed up drop to 1000rpm idle. Then put it on gear and it goes nowhere. As soon as i stepped on the gas it wants to die and can maintain. I did snap a hose on the solenoid valve the hose going to the pressure sensor on saturday. I try to put it together and put crazy glue around it. It hold. and after the drive on sunday i though everything was all good. Anyone selling a solenoid valve by any chance? can it be bypass? help! its also an 86. Link to comment Share on other sites More sharing options...
Jehu Posted March 23, 2009 Report Share Posted March 23, 2009 Status update... I hear the pressure sensor on the firewall next to the MAP sensor clicking...I think it's working right. What's the easiest way to check for a boost leak w/o a compressor (or who has one local to me)? Link to comment Share on other sites More sharing options...
Fanta Posted March 23, 2009 Author Report Share Posted March 23, 2009 Matt, Boosted77 - has a home made leak checker. He actually also owns an 86... hmm Link to comment Share on other sites More sharing options...
Jehu Posted March 23, 2009 Report Share Posted March 23, 2009 Get it setup and get me going again! lol :driving: Or you might see a surprisingly similar SQ for sale on here soon... Link to comment Share on other sites More sharing options...
Recommended Posts