jteckmann Posted February 24, 2010 Share Posted February 24, 2010 Where is the fuel port in this thing ? . . . I have look all over it and i can NOT find the Tire valve stem looking deal for checking fuel pressure . . . buddy of mine said i could use a tire gauge on it looking unit . . . I saw no such device :dunno: I'm stuck at home :fs1: time to crush it ? :dunno: ? Mike The test port is on the side of the TB facing the driver's fender/brake reservoir. Just below where the intake hose clips on. It does not look like a valve stem. IIRC it's an allen head screw that you take out, then you thread your pressure gauge in. I just bought a small cheap gauge at the store that I left permanently mounted there, so I can monitor fuel psi whenever I check under the hood. Link to comment Share on other sites More sharing options...
AMC-MJ Posted February 24, 2010 Author Share Posted February 24, 2010 :ack: Wonderful, i don't have a gauge of that style :wall: it its a round dial gauge with a valve stem looking end on it simulair to that of a tire gauge I got it for use on my 92' GM 350-TPI & 95' Ford 5.8L-MPI :mad: . . . Useless for a TBI engine i see . . . Mike Link to comment Share on other sites More sharing options...
mythreesons Posted February 24, 2010 Share Posted February 24, 2010 Just curious enough to ask............ Don't worry, it doesn't involve buying a part, yet........... What happens if you unplug the O2 sensor and then start it up? Yes, in most systems, that means open loop mode, but I'm not real sure what limitations are under open loop mode. Scott Link to comment Share on other sites More sharing options...
Backroads Posted February 24, 2010 Share Posted February 24, 2010 I'm very new to a 2.5 but it looks like when you first open the throttle, thats when its doing something funny. Could it be the o2 sensor? Link to comment Share on other sites More sharing options...
AMC-MJ Posted February 24, 2010 Author Share Posted February 24, 2010 :dunno: I have no clue :dunno: Mike Link to comment Share on other sites More sharing options...
AMC-MJ Posted February 24, 2010 Author Share Posted February 24, 2010 Not sure i never tried it . . . Mike Link to comment Share on other sites More sharing options...
jteckmann Posted February 24, 2010 Share Posted February 24, 2010 Hard to tell exactly what's going on the vid - I can't see down the TB what your fuel spray is like, and I can't make out what you're saying over the engine noise. What I got from the vid is that it starts/idles fine. Once you start applying throttle it stumbles, idles rough, and then dies. Couple of quick questions - when it stumbles, is there a heavy gas smell? i.e., does it seem like it's dying because it's getting too much fuel, or not enough? Second, if you just start the truck and let it idle, how long until the symptoms appear? Will it start stumbling after it has heated up, or will it idle fine and the stumbling starts only after you start giving it throttle? If the trouble starts only after you start giving throttle, I'd check the fuel system first. If the problems start regardless as soon as the engine warms up, then I'd check the emissions/O2/EGR. The fuel pressure test port is on the driver's side of the TB right under where the air intake clamps on. On mine it was a recessed allen head plug that I needed to remove to thread the tester gauge into. Pressure should be 15psi. On the other side of the TB (facing the valve cover) there's a bowl-shaped part hanging down - that's the pressure regulator. Inside the bowl there's a rubber diaphram and a tension spring. I finally found my Chilton's book, so I'm paraphrasing out of it: the book says the regulator is adjustable (on mine it wasn't, but that may have been because a previous owner replaced/repaired it at some point) If it's adjustable, there should be a screw underneath. Turning clockwise to increase pressure, counterclockwise to decrease. 1. If fuel pressure is considerably higher than 15psi and adjusting regulator fails to lower it, then inspect the fuel return line for blockage. 2. If fuel pressure is below 15psi and adjusting regulator fails to raise it, then do a 2nd test by momentarily pinching off the fuel return line (the one located closest to the regulator, on the side towards the valve cover) while engine is idling and check changes in pressure. a) If pressure momentarily rises, then replace pressure regulator (a rebuild kit that has the rubber diaphram, new spring, and gasket should be about a $20 part) B) If pressure does not rise, recheck the fuel supply line for blockage, the fuel filter, and the fuel pump. It's possible that even though the pump and filter are relatively new, there was debris in the tank that has clogged them, or there is a bad connection/ground, or the new pump was a lemon. If fuel pressure checks as okay, you can check the throttle position sensor (TPS) It's on the firewall side of the TB, right below where the fuel lines enter. Search this site for "TPS" and there are a couple good threads that give instructions on how to test and adjust with a multimeter, and I'd clean up the connections really well. If you want/need to swap it out for a new one, it's about a $50 part. Also check the injector itself. Remove it by carefully unsnapping the connector (+20 yr old plastic gets very brittle) and removing the screws on the retaining ring. Use a pair of pliers to grab the top collar of the injector and slowly rock it back and forth while pulling up. Careful not to twist it or you can break the locating tab. Clean it up and take to a shop to have it tested. If you need a new one, check the earlier thread about options - OEM replacements are pretty expensive ($200). A couple places sell rebuilt ones for around $80-$100. Personally, I substituted an injector from an early 90's Chevy 5.7 that I pulled from a junkyard for $10 and then had tested to make sure it worked. That worked fine for me, and I haven't had any changes in performance or economy in the +1yr I've been running it. If it turns out it's not a fuel problem, then I'd move on to emissions/control systems: - Check that all vacuum hoses are hooked up and in good shape. On an old truck, there's bound to be some leaks, and they can cause some weird gremlins. - O2 sensor - I don't know how to check this with a multimeter, hopefully someone else does. I just replaced it on mine, because I figured it couldn't hurt on a 23yr old truck. IIRC, it was about $60. - Check the EGR valve. Let it idle until it gets to normal operating temp. Disconnect the vacuum hose to the EGR valve and hook up a hand vacuum pump. If it's working right, the idle should stumble/stall when you apply vacuum. If idle stays the same, then the valve is bad. Find the EGR valve solenoid - it should be located on the passenger side fender, close to the ICU/coil. There's an input hose that runs from a manifold vacuum source, and there's an output that runs over to the EGR valve. Pull the hose from the input and check to make sure it's getting vacuum from the manifold. Then hook up your gauge to the output - with the engine idling, vacuum should be zero. If vacuum is present, the solenoid is bad. Then, disconnect the electrical connector to the solenoid and now you should get a vacuum reading. If vacuum is still zero with the solenoid disconnected, then the solenoid is bad. - The final thing I can think of is the manifold pressure (MAP) sensor, which helps control the air/fuel mix. It's mounted on the firewall, almost directly behind the valve cover, with a vacuum hose that leads from the sensor to the manifold. There's a 3-prong connector leading to it. I have hand-written notes in my manual that say "engine off, sensor connected, ignition on - check middle prong, should be 4.5-5v. Start engine, voltage should change and fluctuate with rpm. If not, replace" _________________________ That's about all I can think of. Sorry if it seems like I'm just shotgunning at it, but with a +20 year old truck it never hurts to go back and re-check everything. I tried to follow the notes and steps I took when I had similar symptoms. In my case, it turned out to be two separate problems - First was a faulty injector that made it practically undriveable. When I got that fixed, it ran but still stumbled occasionally, and that's when I discovered a fuel pump that was failing intermittently because of a bad ground. After that was fixed, the truck stopped stumbling, but it still idled/drove rough. I went back through all my sensors, cleaned up the connections, replaced all the vacuum lines, replaced my MAP and O2 sensor - and the truck operated much smoother, practically as good as new. Good luck, and I hope you can get it figured out :cheers: Link to comment Share on other sites More sharing options...
mjeff87 Posted February 24, 2010 Share Posted February 24, 2010 unplug the O2 sensor and run it, see if it changes any. If not, disconnect the wiring connector from the EGR solenoid (passenger side, above the evap canister) and run it, see if it changes any. Definately sounds to me like an A/F ratio mixture issue. If neither of those changes anything, I'd suspect the injector (but those are quick, no $$$$ checks you can make first) Jeff Link to comment Share on other sites More sharing options...
1987Comanche Posted February 25, 2010 Share Posted February 25, 2010 I'd vote fuel delivery problem since it idles ok but bogs down when you give it gas. FP regulator, injector, and/or TPS. You have plenty of air and, from your list of tune up parts, spark as well. What do the wires leading to the injector look like? Any chance of a high def video?? Link to comment Share on other sites More sharing options...
AMC-MJ Posted February 25, 2010 Author Share Posted February 25, 2010 :hijack: can i do that ? :dunno: i guess so :hijack: OFF track: "Video" I don't know about an HD remake but i have lots of awesome Videos on my you tube account some of the 2.5er some of the Studebaker 6x6 and tons & tons of ATVing videos and so on . . . Do subscribe n snoop around . . . ON track: So i just simply fire it up and unplug one unit at a time, the unit that causes no change in its operation is the bad part or parts ? Mike Link to comment Share on other sites More sharing options...
aemsee Posted February 25, 2010 Share Posted February 25, 2010 Mine stumbled just like that. Was the EGR. Made a block off plate. Some day I'll change the valve. But since it only sees about 300 to 400 miles a year right now....... Link to comment Share on other sites More sharing options...
Wildman Posted February 25, 2010 Share Posted February 25, 2010 Nice video :popcorn: OK.......I'm not real up on the 2.5.........so.....Here's the Renix fuel tech manual if you need - http://www.lunghd.com/Downloads_and_Lin ... manual.pdf Just for S&G, what are you running for plugs??? Have you pulled a plug to see what it looks like when it runs like that??? wet with gas, dry, running hot??? I'm tossing that out, cause, it idles kind of rough, when you give it gas, it chokes right out. I know, I've been reading your posts, and what you have done. Also..........did you check the EGR valve??? Unplug the vacuum line to the EGR, and plug the rubber line, and see how it runs. I know on a 4.0, if the EGR is shot, it will choke the engine right out, even in idle :eek: Link to comment Share on other sites More sharing options...
AMC-MJ Posted February 25, 2010 Author Share Posted February 25, 2010 I forgot the brand of plugs but i haven't pulled them since i installed them . . . It only idle rough once its acting up when it stalled in the video ? i could of shut the key off wait 5-15seconds fired it right back up instantly it would of idle smooth again . . . It would rev out perfectly 3-5 time then go right back to bogging out . . . When i'm watching the fuel flow from the Injector while reving it up i notice the fuel flow fading away not increasing . . . Mike Link to comment Share on other sites More sharing options...
Wildman Posted February 25, 2010 Share Posted February 25, 2010 Well......you have 2 topic going on this same subject :D And in the other one........Mr. Aemsee mentioned the EGR valve, and he know 50+X's what I know, so there's 2 votes for the EGR. Disconnect it and see what happens. I ask about the plugs, because you should be only running Champions, nothing else, and with it spitting like it is when you add gas, the wrong plugs will mis-fire, causing about what your movie is showing :D Link to comment Share on other sites More sharing options...
AMC-MJ Posted February 25, 2010 Author Share Posted February 25, 2010 Some how i highly doubt the plugs have much to do with it as since the tune up it logged in 1,000 trouble free miles :dunno: Mike Link to comment Share on other sites More sharing options...
AMC-MJ Posted February 25, 2010 Author Share Posted February 25, 2010 this was a progressive problem that has now gotten to the point where it won't drive any more . . . Tossing randum parts at it has now gotten uncost effective . . . Mike Link to comment Share on other sites More sharing options...
Wildman Posted February 25, 2010 Share Posted February 25, 2010 Some how i highly doubt the plugs have much to do with it as since the tune up it logged in 1,000 trouble free miles :dunno: Mike OK.......so then you don't think you should even pull one plug to see what it's tell you on the running condition of the engine :hmm: Is this also Assuming that the wire have 1000 miles on them, and nothing would be wrong with them either :hmm: Well......good luck on you problem solving. Just keep throwing new parts on it, I'm sure some day you'll get it running again :D Link to comment Share on other sites More sharing options...
AMC-MJ Posted February 25, 2010 Author Share Posted February 25, 2010 it start by running like that twice before only it would stumble bumble stall out and if ya let it sit for 15min it fire back up and run perfectly for several weeks after ward . . . Now it simply started to stumble and bumble with no recovery . . . tis why i suspected the coil . . . was the only new start since this started . . . rest of the parts had been change loing before this . . . Ok I unplugged the TPS truck ran the same so i re plugged it in, then i unplugged the O2 sensor truck ran the same, Then i unhooked the EGR valve vacuum line truck ran the same . . . I even manually stuck my finger inside and pushed the EGR valve it made not effect on the truck at all . . . So everything is working ? or Nothing is working ? I started bumming and wanting to crush it, :idea: So to pick up my spirits installed my new rear tires :D pics will be posted in my project thread shortly . . . So after i thaw out i'll go check the plugs and take photos of them ;) Mike Link to comment Share on other sites More sharing options...
AMC-MJ Posted February 25, 2010 Author Share Posted February 25, 2010 it start by running like that twice before only it would stumble bumble stall out and if ya let it sit for 15min it fire back up and run perfectly for several weeks after ward . . . Now it simply started to stumble and bumble with no recovery . . . tis why i suspected the coil . . . was the only new start since this started . . . rest of the parts had been change loing before this . . . Ok I unplugged the TPS truck ran the same so i re plugged it in, then i unplugged the O2 sensor truck ran the same, Then i unhooked the EGR valve vacuum line truck ran the same . . . I even manually stuck my finger inside and pushed the EGR valve it made not effect on the truck at all . . . So everything is working ? or Nothing is working ? I started bumming and wanting to crush it, :idea: So to pick up my spirits installed my new rear tires :D pics will be posted in my project thread shortly . . . So after i thaw out i'll go check the plugs and take photos of them ;) Mike Link to comment Share on other sites More sharing options...
AMC-MJ Posted February 25, 2010 Author Share Posted February 25, 2010 Plug #1 Plug #2 Plug #3 Plug #4 Hopefully you can look at these, hey you part "bla bla" then shazzam the truck runs problem free for another 22 years :thumbsup: . . . Mike Link to comment Share on other sites More sharing options...
AMC-MJ Posted February 25, 2010 Author Share Posted February 25, 2010 Plug #1 Plug #2 Plug #3 Plug #4 hopefully this is helpful in some way . . . Mike Link to comment Share on other sites More sharing options...
mjeff87 Posted February 25, 2010 Share Posted February 25, 2010 they look ok to me it's hard to tell from your video, but is the vaccuum line to the MAP sensor hooked up? Also looks like the grommet is cracked on the rear vac line on the valve cover (but maybe it's just shadowing in the vid). there should have been a noticeable change in idle behavior when you manually opened up the EGR valve (assuming it was idling smoothly when you did). Wouldn't hurt to take the valve off the manifold and verify that it's closing completely. Jeff Link to comment Share on other sites More sharing options...
AMC-MJ Posted February 25, 2010 Author Share Posted February 25, 2010 all looked intact and sound to me when i was checking it out . . . Video wasn't the best but i seems as tho it really wasn't much of a help . . . Unplugging the TPS did nothing Unplugging the O2 sensor did nothing unhooking the EGR did nothing . . . Multi part failure ? Mike Link to comment Share on other sites More sharing options...
mjeff87 Posted February 25, 2010 Share Posted February 25, 2010 backprobe the injector harness with a meter and watch the pulses, see if they are steady/even and change with engine RPM (analog meter would be best for this). If you start seeing voltage drops when the engine is stumbling, you'll know it's something ECU related and can troubleshoot from there. Link to comment Share on other sites More sharing options...
AMC-MJ Posted February 25, 2010 Author Share Posted February 25, 2010 :wall: I can't find my Meter :fs1: this really is pissing me off :hmm: Who swipped my Multimeter :rant: Mike Link to comment Share on other sites More sharing options...
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