Bucking miss fire , I'm out of good ideas
My car started bucking and miss firing on Monday
This all started after I removed my fuel pump in order to fix my fuel level sensor which the float Had fallen off . It took a couple hours of fishing in the tank to get the float so the pump was outside for that time . Eventually I got it Re assembled everything, and the car started right up . I decided to drive the car to work to make sure everything was ok . But it wasn't the car started to buck and miss after it had been in traffic for a while . I started reading up on causes and symptoms and came up with tps as a likely cause. I Re checked all the fuel lines to make sure nothing was leaking or kinked. Since I have a pfc I checked my tps and it was perfect . So I decided to drive the car yesterday again and pay more attention to when it happened , again it happened when I had been driving for a while but much worse this time The car would buck and afrs would fluctuate up to 17 afrs so I stopped immediately and pulled the fuel pump I realized that the relay was hot . I pulled the pump made sure everything was ok and Re assembled everything I bypassed the fp relay and connected power to fp and the fp worked fine no over heated wiring I put on a spare relay I happen to have in my trunk a 40 amp and made it to work wi th out any issues But when I got to work the relay was very hot up . I drove home and the car started with the same symptoms after driving for a while. same issues not as bad as earlier in the mornning but still there. I thought maybe the relay was getting to hot so I replaced it with a hwavy duty relay and started the car no more overheating relay Today I drove the car to work again and ..... same thing Decided I was out of my league and took a video Whats strange to me is the car was fine before I messed with the fuel pump could leaving it out for a couple hours had somehow broken it , but why does this only happen after 30 minutes of driving. If this hadn't happened right after I did the whole fuel pump removal I'd say the cause was bad coilpacks or bad plugs But what are the chances the car was fine one day and bucking the next for no good reason other than it just deciding to give up Tps is perfectly in specs My last thought is maybe some particle is stuck in the injector but again why does it only happen after driving for 30 minutes Before that it works fine Thanks for reading this huge story book |
One thing I forgot when ever I do this and I get the miss fire there is a huge plume of smoke
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Pump is likely over working for some reason and getting hot or eventually not able to overcome the blockage or whatever is causing it to get hot.
The plume of smoke is likely detonation so be careful. Be sure the filter on the pump is installed correctly and nothing is in the way of flow. It's clearly something related to the fuel pump and again you should be really careful until you figure it out. |
Pumps are so cheap, I would start by just replacing the pump and see what happens. Definitely sounds like it's malfunctioning and causing excessive current to be drawn, hence the hot relay.
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Originally Posted by DC5Daniel
(Post 11976983)
Pumps are so cheap, I would start by just replacing the pump and see what happens. Definitely sounds like it's malfunctioning and causing excessive current to be drawn, hence the hot relay.
I'm going to try replacing coil packs / wires / and plugs , and seeing if that fixes the issues if not I think I'll replace the pump itself |
Have you checked your fuel pressure? Has the fuel filter been replaced? Have you double checked all the connections (elec and fuel lines)?
It's probably the pump, but you want to eliminate as many variables as possible. These things are so old that touching a perfectly fine and working component may break it. |
Originally Posted by TomU
(Post 11977049)
Have you checked your fuel pressure? Has the fuel filter been replaced? Have you double checked all the connections (elec and fuel lines)?
It's probably the pump, but you want to eliminate as many variables as possible. These things are so old that touching a perfectly fine and working component may break it. but yes I will re double check the connections. no i havnet check FP no gauge to check it with.. |
Originally Posted by Tem120
(Post 11977054)
no i havnet check FP no gauge to check it with..
Low pressure would mean the pump or some sort of clog. Normal could mean injectors or control system. If you have a new pump, that should rule that out. |
FYI, you can't check fuel pressure with a PowerFC, there is no stock sensor that logs fuel pressure.
Most likely it's your pump. A buddy of mine always said "when something goes wrong, look at what you just got done screwing around with". I assume you have an aftermarket pump. Many of them nowadays are cheaply made, it's possible the pump itself didn't like getting messed around with. Could be connections to the pump as well, obviously it had to be unplugged in some way to get the assembly out of the car, that electrical connection may not be the best. The fuel hose that goes from the pump to the top of the fuel pump hanger assembly is very critical, if it's leaking you'll lose fuel pressure but with no obvious fuel leak, as it will be inside the tank. A fuel pressure gauge is cheap at an auto parts store, T it into the feed line to the engine and tape it to the windshield. Fuel pressure should go up and down with vacuum/boost, the fuel pressure regulator on the engine keeps fuel pressure at a set pressure above what is in the intake manifold. If you see pressure dip or spike when you have a misfire, there you go. But, I'd just pull that assembly and go through everything carefully first. Dale |
I bought the stuff to make a temporary fuel pressure gauge
I really don't want it to be the fuel pump but I'll check it. I'm also going to check the plugs and swap coilpacks with a spare set I had but I have a feeling it's gonna be the fp I just don't understand how take the pump out for an hour is enough to break it |
What pump do you have?
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sard 280lph
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Originally Posted by Tem120
(Post 11977151)
I bought the stuff to make a temporary fuel pressure gauge
I really don't want it to be the fuel pump but I'll check it. I'm also going to check the plugs and swap coilpacks with a spare set I had but I have a feeling it's gonna be the fp I just don't understand how take the pump out for an hour is enough to break it Take the sock off and see it there is any thing blocking the pump and of course replace the sock if needed. |
Yeah I'm thinking fuel pump now
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Could be crud knocked loose while messing with the float/pump and plugged up filter causing more back pressure and more work on the pump...
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So new pump arrived today and ups did a great job of destroying the pump for me
https://cimg8.ibsrv.net/gimg/www.rx7...c472a95340.jpg Broken fuel pump courtesy of ups I'm quite a bit upset and I've been in this position before and basically there is no winner My question to the collective rx minds is easy can I remove all the broken parts and run a hose in between Or is that little floater that goes into the white broken plastic some kind of pressure regulator |
http://densoautoparts.com/sites/defa...-pump-2014.png
CHECK VALVE , AND RELEIF VALVE ARE BROKEN .. can I assume this pump is useless? |
You may have better luck working with the vender you bought it from for poor packaging. It should be packed to survive transit.
Regardless, it's a bummer |
No it was packaged well some idiot just threw it and it landed badly this isn't the first time ups or usps have destroyed things on the way .
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well that really sucks...
*cough* singe turbo... ahemmmmmm *cough* |
Originally Posted by 96fd3s
(Post 11980223)
well that really sucks...
*cough* singe turbo... ahemmmmmm *cough* the turbos are the ONE thing working.. |
Originally Posted by Tem120
(Post 11980224)
that doesnt fix my initial issue though!
the turbos are the ONE thing working.. you can have my new unused walbro 250 for free if you go single, lol. I bought it and never installed it..installed the 400lph instead |
Ok So it turns out it WAS the Fuel pump.... after swapping the FP with a walbro , some cutting and re wiring had to happen , BUT 2 days and so far so good .
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