fuel pressure problem

[Nezdude87]

I'm stuck 2 hours from home, had my car towed. Was driving fine then fell flat on its face. Coasted off the road and it restarted fine. After a minute or so, the rpms drop to 200 and it struggles to take gas. If I try driving it just cuts out and either dies or sputters so bad it's undriveable. The mechanic said the fuel pressure is great when it starts up, then after a minute just goes to nearly nothing out of nowhere. He believes it's an electrical issue and can't find a problem so far. He said he's got a few more things to try, and I mentioned the main relay just as an extra thing to check. Anyone have an idea? I'm stranded, living out of a super 8 for the day. Really don't wanna leave it so far from home.

[mtnbikaah]

I'm just guessing here... Could be the igniter in the distributor on the fritz...

[Nezdude87]

Would that make the fuel pressure drop suddenly? The distro is just a year old if that, not saying it's impossible for a relatively new part to malfunction though. The last update I got before the garage closed was that while driving, the rev limiter kicks in at 3k. If he unplugs the main relay and plugs it back in it runs fine for about 30 seconds (they tested a brand new relay to be sure that wasn't the cause) then the fuel pressure drops again. He really believes it's electrical, they're having someone else look at it tomorrow. If the fuel pump is going out, would it have normal pressure then low or no pressure after driving for 500 yds or running for 30 secs to a minute? Or would it be steady low pressure the whole time? He claims since it's firing up with normal pressure and idling and driving fine for a while at first it shouldn't be the fuel pump. I've always heard they could go out instantly or slowly, though.

Also, like I said, I'm out of town. I don't know how good these guys really are since I don't deal with them regularly. I think they may be over thinking this due to the F23 swap.

[Sordz]

So is the fuel pressure regulator good? I would assume thats the first thing they would check but you didnt say. Fuel pump is not likely as all the failed ones I have seen they either work or do not work, but anything is possible I suppose. Sounds like there is a CEL, what codes?

[Nezdude87]

Egr and o2 have been on since day one of owning the car for two years. Never had the money to fix it. And I'll ask and see if they checked the regulator. I'm sure they did, but I'll still ask.

[Sordz]

I would also ask them to check the timing. 02 shouldnt make the car not run but I think you could unplug the bad sensor so that it cant send any signal to the ECU and see if that matters.

When the car starts up it runs rich for a short time, that is probably why you are having it run fine for a short time. I would also inspect the spark plugs and fuel filter. Hopefully they figure it out, good luck

[southsidecb7z]

A fuel pump definitely CAN become too weak to deliver the amount of fuel needed to run the engine properly. I actually have one at the moment, although not in a cb7. Rev limiter being at 3k sounds like "limp mode", though im not sure if a weak fuel pump would ingage that.. Are there any cel's?

[Nezdude87]

So here's what's happened. They called a tech hotline or something to see if they could get help yesterday. The tech denied help since I'm running a frankenstein f23 build, I guess that prevented them from diagnosing anything, which is totally understandable on their end. However, he said if he would unplug the main relay and plug it back in (they tested two main relays to be sure), the car would fire up and run fine for a minute or so then go back to the low rpms, and cutting out while driving. He then went back over each individual wire, checking voltages. Everything looked good, the ECU wasn't taking a dump or anything. He said he added an extra ground somewhere and closed up shop for the evening yesterday. This morning, he was getting ready to try some more troubleshooting, and the car just starts up and runs like a champ. They drove it 30 miles the first trip, and took it out around town two more times before telling me to come check it out. This SAME thing happened to me last time I had it looked at by the mechanics I trust here at home. Had it towed with the same identical problem back in January or so, the mechanic started it a couple days later, and couldn't find one single thing wrong. Although it acted up and these guys did see the problem, they told me they couldn't really go further with it and charged me less because they know they didn't really fix it, lol. At least they were honest and didn't rape me with labor (spent two full days on my car alone and only charged me 200, sounds high but I was thinking it would be WAY worse).

What in the world could this be? I drove it home, a straight 2 and a half hour drive, with absolutely no problems whatsoever. I can floor it and it won't miss a beat right now either. I know this will likely act up again, and it comes out of nowhere, so it makes me trust my baby a little less. The two cel codes are for egr and o2, but as I said before, they've ALWAYS been on, and I've had the o2 unplugged, and the egr unplugged, and it made no difference in running. The o2 and egr were actually unplugged the last time this happened, and plugged up this time, and the symptoms were no different.

Oh, slightly off topic, but I got a job paying about 1000 bucks every 2 weeks, that's why I was out of town in the first place Tuesday. I have no serious bills, so hopefully before the summer is over, I'm getting an H22 swap. I just need this old f23 to run me back and forth to work.

[Nezdude87]

Alright, I have a little more specific info now. It acted up again, it does in fact go into limp mode. The rpm's will not go over 3k, it bounces. Since I'm at home, I can actually spend time looking at the problem myself. The "tick" we hear from our main relays when we first turn our keys and the fuel pump kicks on, I hear that tick while the car is running, then it goes into limp mode. I can hear the tick repeatedly and then the car will just stall. If I start the car without turning my key back to the first position (the position to remove it), it will just try to start and take no fuel. If I turn the key back and then start it, it starts up and idles perfect. When I give it fuel, I'll hear the tick, and bam, limp mode again. It sounds like the relay is going in and out, and the people who worked on my car earlier this week said they tried two main relays and the car acted the same. Could there be a short? I recorded a video of what's going on, I can upload it if need be. It's just the rpm's basically, but if it'll help diagnose this then i'll do it.

https://www.youtube.com/watch?v=6PAN7APzi1w

there, i went ahead and uploaded it. turn the volume up and listen, you can hear a humming the entire time as well, and the engine just sounds awful. also, the first time i rev, listen for the main relay click, then look how low it idles

[Nezdude87]

An update: The mechanic believes he has fixed it. We don't know 100% for sure since it's possessed and wants to run perfect after a few days of limp mode, but personally I believe it MAY be okay this time.

I've never heard of this part, but he said he replaced the "igniter box" or something like that. I can't remember what he called this part exactly, but I believe I found it here: http://www.ebay.com/itm/94-97-Honda-...-/190550881136 . It's on the driver's side, off to itself from what i could tell, around where the strut bolts if i'm not mistaken.

I know that's for a cd5, but it looks identical to the part he showed me, just so you know what i'm talking about. He had another cb7 setting there (same paint and all, lol) and decided to just go to town on mine swapping out sensors and parts one at a time i guess. He said it was in limp mode, then came out after putting that part in. He let it just set there and idle for an hour, then drove it about 50 miles. Without turning it off, he told me to come check it out. I tested it up and down the highway, running the living dog crap out of it through the first couple gears, and it took fuel perfectly and revved all the way to redline. I can't find much info online about this part and its function, he mentioned something about a connector on something to do with the injectors, i don't know if this was the part he was talking about, but I do know for a fact this part was changed on my car.

edit: http://www.ebay.com/itm/90-91-92-93-...94a14e&vxp=mtr . that's it, exactly. could that malfunctioning cause limp mode?

[Qiko]

wow, good stuff here. Thanks for sharing. I am curious myself if this resolves your issue with limp mode.

[Nezdude87]

Well, it acted up again. Went into limp mode this morning after running for about 10 minutes. It didn't die out and didn't stop taking fuel, so I drove it home. I'm finished with it for now. A friend sold me a 2003 buick century for 1500 bucks on a payment plan, so that's gonna be my daily. It needs a new bumper and fender, but everything else running wise is perfect. My poor accord will have to wait about a year, I have to get on my feet and get an apartment before I can do anything to it. It's this stupid f23 swap, no one can figure anything out. If I had a spare ECU to just try out I'd do that, but I don't want to spend that much money on a guess alone. I'll be doing the f20b swap, or maybe h22, just depends on where my mind is at the moment. New motor and ECU and harness and all, so I'm fairly certain that will cure the issue, haha. The old f23 was slowly on its way out anyway, just sucks that it's an electrical issue, it had another year left at least.

[Nezdude87]

Sorry to keep bumping this thing, but yesterday I unplugged VTEC, it was hardwired into the ECU. It still went into limp mode after driving a couple miles. Today, I needed to drive it 15 miles to my fiancée's house to park it. I'm moving out of town and need it somewhere safe. I decided to reset the ecu randomly, I had cleaned the ground on the thermostat yesterday as well (still limp mode afterward). I reset it, jumped in, and drove the crap out of it. It had noticeably more power than before and didn't go into limp mode at all. I'm gonna do some more driving in it this evening, but I was wondering if limp mode stays on even after a problem is fixed until you reset the ecu.

[cloudasc]

Your symptoms almost sound like a faulty o2 sensor. I've had mine fail and cause intermittent problems with fueling, it would hesitate and stutter, but when I would WOT it would act fine (as that's when the ecu uses its predetermined fuel/ignition maps and ignores the 02 sensors input). It took over 2 hours of driving with it stuttering intermittently before it threw a cel. If in fact you are going into 'limp mode' your check engine light should come on, which can help determine the issue. Do you see your check engine light come on and turn off when you first turn the key to acc/on?

[Nezdude87]

I think I said in an earlier post that my EGR and o2 are throwing codes. I've checked the codes myself. It's been that way for a year and a half, so that's why I was thinking it wasn't the cause of limp mode. I may try a new o2 sensor when I get paid just to see. A friend of mine said his cb7 went into limp mode over the o2 sensor (stock motor and ecu), so I guess it can't hurt to try.

Oh, I just got back from another "test run," haha. I let it warm up, then held it at nearly wot through first and second gear. After that, I drove normally. Before I got out of 4th gear, the car gave me the "limp mode jerk," as I've dubbed it after feeling it countless times this past week, lol. So yeah, back in limp mode.