FarmerBrown5 Posted February 12, 2016 Share Posted February 12, 2016 Alright guys, I have a '92 Comanche that has been having some issues. Not on every start up, but most of them it will crank for a long time or crank hard. There is no fuel pressure in the rail. I have changed the injectors to 4 hole Bosch 943's which, as I understand, are Fords and they put out 18.25lb/hr. After changing them it seemed to start a little better, but I still had no pressure in the rail. I changed the Fuel Pressure Regulator and still no improvement. Now to back up a bit...Before I ever started working on the issue, the Jeep would run great, but if I was in 3rd gear and run the RPMS up to 2 grand it would get juggy, or feel like it was starving for fuel. After the injector swap and new Regulator I took it for a spin and everything seemed fine....until I had to climb a hill at the end of our road. I was in 3rd and it did not want to climb it. Once I got up the hill I went around the block and it started acting up in 2nd, 3rd, and 4th. It felt to me like it was not getting enough fuel, or too much fuel. I could feel shaking under my feet like something was rattling around when the truck didn't wanna go. Before I put the old injectors back in to see if that solves the issue, I thought I would ask you guys what you may think is wrong. Thanks in advance! Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 12, 2016 Share Posted February 12, 2016 There is no fuel pressure in the rail. How did you determine this? With gauges? It wouldn't run at all with no fuel pressure.... Link to comment Share on other sites More sharing options...
FarmerBrown5 Posted February 12, 2016 Author Share Posted February 12, 2016 There is no fuel pressure in the rail. How did you determine this? With gauges? It wouldn't run at all with no fuel pressure.... I should have clarified....I do not have pressure when the engine is off. When I try to release pressure at the test port on the rail there is no pressure to be had. Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 12, 2016 Share Posted February 12, 2016 That's not the issue. My fuel rail leaks down to zero psi about 2-3 minutes after I shut the engine off - most all do. There is a check valve at the fuel pump, and even with a new pump I still leak off all the rail pressure in about 2-3 minutes. If you haven't already, rent a set of gauges from Autozone or similar and test the pressure at the fuel rail Schrader valve port to see what's up. With vacuum hooked up to the regulator and the engine idling you should read ~31psi. Disconnect the vacuum line and pressure should jump up to ~39psi. Then shut off the engine and see how long it takes the pressure to leak down. 3-5 minutes is fine. Link to comment Share on other sites More sharing options...
FarmerBrown5 Posted February 12, 2016 Author Share Posted February 12, 2016 10-4! Thats about as fast as mine leaks off as well. I will still get the gauges and test it. If the pressure checks out, what would you propose to do next? I did not reboot the computer like some people say they do because the truck started and idled like normal. Not sure if that would be something to still consider or not. Link to comment Share on other sites More sharing options...
mikekaz1 Posted February 12, 2016 Share Posted February 12, 2016 your fuel pump could be dying or your filter screen on the head of the fuel pump could be clogged too Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 12, 2016 Share Posted February 12, 2016 Did you check for fault codes? http://comancheclub.com/topic/28111-reading-obdi-91-and-92-mj-fault-codes/ Link to comment Share on other sites More sharing options...
FarmerBrown5 Posted February 12, 2016 Author Share Posted February 12, 2016 I got 12, 35, 33. They showed in that order. I do not have A/C or an electric fan. I'm guessing thats why they showed? Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 12, 2016 Share Posted February 12, 2016 ^^ No worries there........... Link to comment Share on other sites More sharing options...
comanche503 Posted February 12, 2016 Share Posted February 12, 2016 I have the 92 eliminator with auto trans, just got it with the same issue. Got the same codes. Makes a bogging noise if you try to get up past 2500 rpms. Hates hills. At first i thought it was slipping in the trans but then i tried revving it up in park and neutral, still got a bogging noise and loss of power-rpms at around 3000rpms. The more pedal i give it the worse it gets, unless I really ease into it. I have refreshed the grounds and connectors, new vac lines,,new fuel filter, new vac res, cleaned dist, new trans fluid with lucas stop slip, and seafoamed everything. I am thinking it is the TPS. Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 12, 2016 Share Posted February 12, 2016 I had this symptom on my 91 when I first got it. After much troubleshooting it turned out to be a clogged cat. Link to comment Share on other sites More sharing options...
comanche503 Posted February 12, 2016 Share Posted February 12, 2016 The guy at napa suggested it was a clogged cat. Link to comment Share on other sites More sharing options...
mikekaz1 Posted February 13, 2016 Share Posted February 13, 2016 My buddy has a 96xj that was used as a yard truck at a junkyard. So it had all the bogus gas poured through it. It idled like crap. And WOULDNT go past 2500rpm while driving. And gave issue in park at around 3000-3500rpm. It ended up being the fuel strainer in tank was clogged nearly solid. I'd pull your sending unit and check the screen. Link to comment Share on other sites More sharing options...
mikekaz1 Posted February 13, 2016 Share Posted February 13, 2016 You may also be able to tell by jumping the ballast resistor with an online amp meter and see what the pumps pulling for amperage. Id imagine if it were clogged it would be pulling high Link to comment Share on other sites More sharing options...
cruiser54 Posted February 13, 2016 Share Posted February 13, 2016 Cruiser’s Vacuum Test for Exhaust Restriction Your vacuum gauge should come with an instruction booklet outlining this procedure. Hook the vacuum gauge up to a source on the intake manifold. Start the engine and note the vacuum reading. It’s usually 17 to 21 inches of vacuum. Throttle the engine up to 2,000 to 2,500 RPM for 20 seconds or so and the vacuum reading should stabilize to the same reading you got at idle. Let the throttle snap shut. The vacuum reading should shoot up about 5 inches of vacuum higher for a second and then come quickly down to the original reading. If the vacuum reading stays high and comes down slowly with jerky needle movements, you have an exhaust restriction. Link to comment Share on other sites More sharing options...
FarmerBrown5 Posted February 13, 2016 Author Share Posted February 13, 2016 I need a new gas tank, so what I am going to do is order a new pump and strainer since I will be right there. any suggestion on brands? My exhaust could be an issue too. There is a hole where it comes over the axle at the hanger and at the end of the tailpipe. They're far enough at the end I don't think that is a huge issue, but it appears to have the original CAT and a 'new' glasspack. The exhaust has been like this since I bought the truck 2 years ago. Link to comment Share on other sites More sharing options...
Marine1Texas Posted February 13, 2016 Share Posted February 13, 2016 For the exhaust hole just weld it up or patch it, no need to replace and use money on something small like that. CAT is easy to replace and very cheap to replace too, just cut that bad boy off with a sawzall and put a new one on if you thinking of replacing it. no need to even weld it on if you don't want, just get 2 pipe adapters and some clamps. If your in a area like I am in, a 1992 is exempt for emission then you can just hollow it out while still having visual view of it being on the truck! Link to comment Share on other sites More sharing options...
FarmerBrown5 Posted February 13, 2016 Author Share Posted February 13, 2016 My plan was to just patch the holes. IF the CAT is bad Id buy one and punch it out, or just replace it with a pipe. If there is a restriction then I will do something, otherwise I am going to leave it be. Link to comment Share on other sites More sharing options...
comanche503 Posted February 13, 2016 Share Posted February 13, 2016 Do I have to drop the gas tank? It looks like i have room down there to pull the fuel pump. I am going to try cleaning the inlet filer. Link to comment Share on other sites More sharing options...
cruiser54 Posted February 13, 2016 Share Posted February 13, 2016 Do I have to drop the gas tank? It looks like i have room down there to pull the fuel pump. I am going to try cleaning the inlet filer. Remove the driveshaft and it's easier to do in the truck. Link to comment Share on other sites More sharing options...
FarmerBrown5 Posted February 13, 2016 Author Share Posted February 13, 2016 just checked the pressure. with Vac I am reading 27PSI. Without I am reading 36PSI. When the truck shutoff it drained to zero psi in 3 seconds.... Link to comment Share on other sites More sharing options...
cruiser54 Posted February 14, 2016 Share Posted February 14, 2016 Should be 31 and 39 respectively. Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 14, 2016 Share Posted February 14, 2016 I changed the Fuel Pressure Regulator. just checked the pressure. with Vac I am reading 27PSI. Without I am reading 36PSI. When the truck shutoff it drained to zero psi in 3 seconds.... What did you use for a FPR? P/n? Link to comment Share on other sites More sharing options...
FarmerBrown5 Posted February 14, 2016 Author Share Posted February 14, 2016 Standard T Series P/N: PR210T Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 14, 2016 Share Posted February 14, 2016 That's correct. Can you replace it with your old regulator and pressure test again? Could be the pressure gauge is off. Link to comment Share on other sites More sharing options...
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