Loyale#1 Posted August 9, 2016 Share Posted August 9, 2016 I have a 94 loyale. When I got it the previous owner had the hose coming into the fuel pressure regulator clamped off. When I took the clamp off the motor ran rough and would eventually die at idle. I replaced the regulator, still having same problem. If you clamp the hose shut it runs fine. Take the clamp off rough idle and dies. Any suggestions? 1 Link to comment Share on other sites More sharing options...
987687 Posted August 9, 2016 Share Posted August 9, 2016 Why don't you hook it up how it's supposed to be hooked up? Link to comment Share on other sites More sharing options...
Loyale#1 Posted August 9, 2016 Author Share Posted August 9, 2016 How is it supposed to be hooked up? 1 Link to comment Share on other sites More sharing options...
MR_Loyale Posted August 10, 2016 Share Posted August 10, 2016 I have a 94 loyale. When I got it the previous owner had the hose coming into the fuel pressure regulator clamped off. When I took the clamp off the motor ran rough and would eventually die at idle. I replaced the regulator, still having same problem. If you clamp the hose shut it runs fine. Take the clamp off rough idle and dies. Any suggestions? Post a pic of the hose aand surrounding are. Way too vague for me ti know which hose you are talking about. 1 Link to comment Share on other sites More sharing options...
Loyale#1 Posted August 10, 2016 Author Share Posted August 10, 2016 1 Link to comment Share on other sites More sharing options...
DaveT Posted August 11, 2016 Share Posted August 11, 2016 That Romex clamp? That's on the return fuel line. That should not be clamped off. Remove that, t in a fuel pressure gauge on the supply side. Link to comment Share on other sites More sharing options...
MR_Loyale Posted August 11, 2016 Share Posted August 11, 2016 (edited) It could be the fuel pump is subpar in supplying pressure so to compensate, they blocked the return line. Only way to know for sure is to measure the pressure as stated above. A clue to the fuel pump might be to listen to how long it takes to charge. With the car off, turn the key to just before starting and you should hear the fuel pump charging the line. It should take about 3 seconds. If it is going much longer, suspect the fuel pump. ETA: Sometimes a failing fuel pump can be brought back temporarily by gently rapping on it with the HANDLE(wooden preferred) of a hammer. So one test would be to remove the clamp and wait for it to die then go in back and gently tap the body of the fuel pump. Try running again. If after a few "rap sessions" (OMG the puns just flow out lol), if the car appears to run OK even for a few minutes, then I would strongly suspect a failing fuel pump. Edited August 11, 2016 by MR_Loyale 1 Link to comment Share on other sites More sharing options...
Loyale#1 Posted August 11, 2016 Author Share Posted August 11, 2016 (edited) Ok so I had the ol lady turn the key while I listened to the pump. It did run for roughly 3 seconds or so. Little background on the car, I picked it up for 400 bucks. Body is clean But ran rough, previous owner said it had sat for a while. I did a complete tune up on it, plugs, wires, cap, button etc. It did run a lot better after that but still didn't idle well and wouldn't start when the engine was warmed up. No check engine light codes. I will try and find a gauge and t it in on the supply line. Anyone know what the factory pump is supposed to put out? Edited August 11, 2016 by Loyale#1 Link to comment Share on other sites More sharing options...
DaveT Posted August 11, 2016 Share Posted August 11, 2016 Did you drain the old fuel? Add new? I'd have to look up the number to be sure, but 20 to 25 psi comes to mind for fuel pressure. If it sat long enough, it could have accumulated some water also. 1 Link to comment Share on other sites More sharing options...
MR_Loyale Posted August 11, 2016 Share Posted August 11, 2016 Another possibility is that either the damper after the clamp is defective or the return line has a leak. 1 Link to comment Share on other sites More sharing options...
Loyale#1 Posted August 22, 2016 Author Share Posted August 22, 2016 New update, wound up replacing the fuel pump because I was having to tap the old one with a hammer handle to get it to spin. After replacing pump I still have to keep a clamp on that return hose for the car to idle well and be driveable. Is there a way to test the dampener? 1 Link to comment Share on other sites More sharing options...
DaveT Posted August 23, 2016 Share Posted August 23, 2016 Could be the pressure regulator is stuck open. Fuel pressure is supposed to be 21PSI. A gauge would help. Not a whole lot in the FSM to help troubleshoot, which surprises me, as they usually have a lot of info. I think the regulator is the shiny thing the return line is connected to. I'd swap a spare one in place to test. Link to comment Share on other sites More sharing options...
Loyale#1 Posted August 23, 2016 Author Share Posted August 23, 2016 That is a new regulator on it. Im kinda stumped. Thanks for all the good suggestions though. Think I could have a vaccum problem? I sprayed starter fluid around all the vaccum hoses and fittings, engine didn't rev. Is there another way to test vaccum? Link to comment Share on other sites More sharing options...
DaveT Posted August 23, 2016 Share Posted August 23, 2016 Need to test fuel pressure in the supply line. Without the clamp on the return line. Low points to regulator, even though its new. High with the clamp points to injector. I doubt it is normal. Link to comment Share on other sites More sharing options...
Loyale#1 Posted August 23, 2016 Author Share Posted August 23, 2016 Ok I will find a gauge after work and get it t'd in the supply line. Will update when I get pressure reading. Link to comment Share on other sites More sharing options...
Loyale#1 Posted August 24, 2016 Author Share Posted August 24, 2016 (edited) Update! So today I got a gauge t'd in my fuel line. With the clamp off the return line gauge reads 22 psi, clamp the return line and the gauge hits 70psi. Another thing I did was pull the vaccum line off of the fpr at idle and nothing changed. So that tells me I'm not getting vaccum there? Should I have vaccum at a idle? This is begining to be very frustrating Edited August 24, 2016 by Loyale#1 Link to comment Share on other sites More sharing options...
Loyale#1 Posted August 24, 2016 Author Share Posted August 24, 2016 (edited) Want to add another thing I unplugged the coolant temp sensor While the car was running and up to operating temp and the idle increased a little. I tested the sensor and got 241 ohms. I read in my chiltons manual the denote should test 2-3,000 cold and around 1,000 at operating temp. Edited August 24, 2016 by Loyale#1 Link to comment Share on other sites More sharing options...
DaveT Posted August 24, 2016 Share Posted August 24, 2016 Sounds like the fuel pressure is good, I would not use the clamp to make it run, or realize that the pump is being overloaded. That might not be good for it. 22psi without the clamp is on normal range. Maybe something wrong with the injector? I suppose a bad vacuum leak could lean it out so much it wouldn't run, but the overpressure then makes up for it sort of. I would think you would be able to hear a vacuum leak that big. A thing to try would be capping off the vacuum taps like the brake booster, the port that goes to the solenoids, etc. I'm trying to think of how to narrow down your problem. I'd just swap in a spare injector. I have yet to have a problem with the mass air flow sensor or the throttle position sensor that caused this trouble. Maybe some else has? The coolant temperature sensor can really screw up running well when it fails in some ways, and it won't cause the CEL to come on. Might be worth putting an ohmmeter on that one, since it's simple to check. Link to comment Share on other sites More sharing options...
Loyale#1 Posted August 25, 2016 Author Share Posted August 25, 2016 I did meter the cts. 241 ohms at operating temp. Have yet to test it cold (waiting on engine to cool down) I don't hear any vaccum leaks, I have even held a small piece of hose to my ear then followed as many vac lines as I could find and didn't hear a single leak. Like I said before I sprayed starter fluid around be vac lines also and engine did not revv. I do not have a spare injector and the parts stores around me do not hardly carry anything for my car so I normally order online. I found this on parts geek part #408-05172345. Is there one you recommend? I have not tried capping off vac lines to narrow down a leak yet. Maybe tommorow after work I will try that. Thanks for the quick reply's and good advice DaveT Link to comment Share on other sites More sharing options...
Dee2 Posted August 25, 2016 Share Posted August 25, 2016 (edited) I have not tried capping off vac lines to narrow down a leak yet. Maybe tomorow after work I will try that. A vacuum test is easy to do and can help you diagnose engine problems and tell you a lot of information about the health of your engine. YouTube has plenty of info on how to use/read a vacuum gauge. http://youtube.com/watch?v=SdlNwm8OHco?version=3 Edited August 25, 2016 by Dee2 Link to comment Share on other sites More sharing options...
DaveT Posted August 25, 2016 Share Posted August 25, 2016 Loyale#1 wrote: I did meter the cts. 241 ohms at operating temp. That isn't good. Way lower than anything I've seen. Table of temps vs ohms from FSM: 14F 7K to 11.5K ohms 68F 2K to 3K ohms 122F 700 to 1000 ohms From measurements on sensors I have, made a while back: 77F 2390 new sensor 185F 400 new sensor 190F 454 1990 sensor Link to comment Share on other sites More sharing options...
Loyale#1 Posted August 25, 2016 Author Share Posted August 25, 2016 Could the cts cause such problems as I'm having? Link to comment Share on other sites More sharing options...
DaveT Posted August 25, 2016 Share Posted August 25, 2016 Need more data points. But if it is say, stuck at 240 ohms, that would be telling the ecu the engine is very hot. It would then not supply enough fuel to get and keep a cold engine running. One of the things it does is control the fuel system like the choke did on carburetor systems. Link to comment Share on other sites More sharing options...
Loyale#1 Posted August 25, 2016 Author Share Posted August 25, 2016 Just tested it cold. 90 degrees out today. Got 1,500 ohms Link to comment Share on other sites More sharing options...
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