JeepYJv8

Hello everyone! so i need your help! please. I will sum it up here first but please read below for all the details

Here's the problemo!!
After i get to about 3/4 petal i see my wide band go up to 20:1 and start popping out the exhaust! i cant seem to find the problem,i seems to only do it under load. here comes the motor details and what i ve done so far and the full story below. please read below before replying. I will leave as much detail as possible, if i miss something or you have any more questions please ask.


Motor Specs
GM 350 TBI
Engine Rebuilt about 500 miles ago (stock bore and stroke)
Mild comp cam/lifter kit
tb spacer
headman small tube headers
dual flowmaster exhaust
machined stock tb (for airflow)
wide band 02 feeds ecm
Fully ported and valve job/springs 193 swirlys

Electronics
1227747 ECM
G2X (moates)
EX remote (tune switcher)
LM-1 Wide band logger/feeding ecm and dash
Winaldl (logging)
Tuner pro (tuning)


Other information
Engine stuffed in jeep wrangler
Art carr 700r4
4:10 gears
36" tires


Ok here is the story and what ive tried so far

A few nights ago while offfroading it leaned out,i was playing with timing earlier so i figured i messed something up. i got back in adjusted my timing back where it was then it seemed fine. i drove it the next day no problems then all the sudden it happened again! to the point i figured it was done for and i was going to break down. (it seems like when it was cool it was ok but once it got hot it happened more and now its doing it almost all the time. so here is what i did so far

I reverted back to factory tune (worse) it ran decent off facory tune before
I added fuel in VE tables ( nothing)
I realized my fuel pressure was down to about 10 psi @ idle so i replaced the (bad fuel filter) it brought my pressure back up to 12.5-13.0 PSI.

At this point i was sure it was ok so i loaded it up on the trailer and it was off to mud bog race.

well i was running late so it went straight from the trailer to the line and i was ready to stomp on it.. as i started to rev her up it felt like no throttle response and was kinda cutting out. At this point i had no choice but to floor it !! well it didnt lean out long i only made it 20ft into the hole and it had no power.

So yesterday i checked the fuel pressure. still at 13.5 and if i blip the gas hard it goes down maybe 1 psi. so i had some spare injectors so i swaped them out. (nothing) at this point i was so mad . i sat on couch and drank beer..

Tonite
checked spark across all 8 cyl. pulling each plug was about a 50 rpm decress with the IAC unpluged. (except for one) as i looked closer i seen melted boot next to header. close enough for arching(i thought this would do it) fixed the wire and changed plugs in cyl 2,4,6,8 still nothing. found leaking vac line to egr (replaced that)

so i changed the est/esc and EGR solinoid, and dist cap checked coil for good spark ( i had them laying around) still doing it but it seems as its improving.

My dad and auto mentor suggested fuel pump from the start but i just dont see it. i will swap it out but im looking for some other ideas also. ( i hate dropping gas tanks!! and my fuel pressure guage shows it ok under the hood..

One last thing it idles ok it rev up great it only does this under a load??? please help

Ronny

iTrader: (1)

Now you are running lean at WOT?

1. did you ever get the underlying tune under control?

2. I did not check prior posts but what size injectors are you using?

3. You say 3/4 throttle. Is that steady at 3/4 or accelleration to 3/4? If the latter it is a AE event so back to the AE tables to add fuel. If you are in PE and you may be at 3/4 you may need more FP or larger injectors or larger fuel pump. I would trust the WB.

4. Your fuel pump may not be able to sustain 13/1. How old is it?

There is a calculation somewhere as to what you need for fuel to support your HP.

Damon

Free-revving an engine in the driveway doesn't take nearly as much fuel as when it's under load at WOT. If you can possibly hook up your FP gague where you can see it while driving (I duck tape mine to the windshield temporarily when doing diagnostics like this) you'll know right away if your fuel system is keeping up with the demands of the engine. It should hold steady pressure under all conditions. If it nose-dives as you step through on it, you've got fuel delivery problems (possibly fuel pump, kinked line, etc).

Trying to tune around fluctuating fuel pressure is an exercise in frustration. Make sure you've got good steady pressure before looking elsewhere for a solution or trying to tune it further.

JeepYJv8

Both of you pretty much got it.

some of the questions you folks asked are here, sorry i dont know how to quote sentences but

Ronny
55LB Injectors
I did get a decent tune going, but some days ran great and others not so much.

Damon
I think you were here today? my neiorbor maybe? or have some physic ability..lol.. i dont remember mentioning that my tune was great at times and sucked other times. but thats whats been happening. and i did have a kinked line. also extending the fuel guage wouldve been a great idea! i wish i wouldve read the posts before i started!! I never realized that moving takes that much more fuel. to run perfect in driveway, but horrible on the road!!

Fuel pump looked old! very old!

End result was the pump, if you feel like reading my novel.. continue on!

I dropped the tank this morning and pulled out the pump! kinked supply line in the tank! it looks like the rubber got old and expanded. It also didnt look like fuel rated hose...

But keep reading it gets better!!!

So i replaced the hose/ filter and reinstalled the tank about 4 hour job!!!
jumped in the truck fired it up without checking anything and hit the road. Still doing the same thing well its worse!!! :0 .. At this point i was looking for matches to light it on fire!!J/K ,

So neiorbors gathered and i heard it was everything from my TB to a cam lobe and broken valves!! .. i decided to moniter my fuel pressure guage once more! I really romped on it. then seen the fuel guage go from 15 psi to 8!! hey now were getting somewhere.. the most ive seen it drop was only 2 PSI. now its dropping 7psi total...

So now i started the removal process of the tank again. Took that fuel pump and tossed it. After debating awhile about buying a new fuel pump gm style or buying the pump for the jeep style which is rated for more output. I decided to keep it gm and the pump was 1/2 the price. Got the pump home and the connector was different! made the day even better, but after looking closer they give you new wiring for a newer style connector. That was nice though i was not in the mood for this but spent some more time on it.
Luckly i test ran it cause the polarity was backwards... if i would've got that tank back in without checking, i wouldve hit the roof..haha ..

So bolted the tank back in and started it up.. I noticed easier starts!! followed by great throttle responce!!and hardly any drop in fuel pressure when i romped on it!! so we jumped in it and it ran great!! i mean locked rear, 36" tires chirping good!

thank you both very much for your help!!!

Ronny

iTrader: (1)

13 lbs fuel pressure at .50 BSFC with 55 lb injectors will support 193 HP

Damon

Glad to hear you got it.

Always a day late and a dollar short when it comes to getting the right advice to the right person at the right time, it seems!