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

 

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.

 

relay is no longer hot I guess i forgot ot mention that relay is now running nice and cool , all wires are running nice and cool .

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.

 

filter was replaced a few months ago , fuel pump was also new it has about 2 years . and 15k miles .


but yes I will re double check the connections.

no i havnet check FP no gauge to check it with..

 

Can't you read FP with a PFC? I don't have one, so don't know. I got a FP tester to measure mine. FSM says you should read 70-106 psi. Think i was getting 45 which i think is normal when under load.

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?

 

sard 280lph

 

Clearly if the relay is getting hot and it happened just after taking the pump out the problem is related to the fuel pump. Typically a relay is going to get hot if it's drawing too much current or not enough. Based on what you have described or it takes about 1/2 hour before you start having problems I'm guessing the pump is getting hot because it's overworked from blockage or not enough current.

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

 

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...

 

So new pump arrived today and ups did a great job of destroying the pump for me



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 .

 

well that really sucks...


*cough* singe turbo... ahemmmmmm *cough*

 

that doesnt fix my initial issue though!

the turbos are the ONE thing working..

 

lol I know, im trying to subconsciously help you to make the decision to go single.
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 .