Idle issues and top end throttle issue

[jasonsvolmo]

1985 svo mustang, kirban fpr, stinger 3 inch exhaust and elbow. La3 swap, dw200 high pressure fuel pump (255) lph

Car will start and idle at 900 cold start, after getting too operating temperature it will reach 1200-1500 (does not fluctuate just chooses between those numbers and doesnt budge) tps set too 0.98. Base idle reset done with timing set too 11 btdc spout disconnected. this car when warmed up will NOT drop below 1200, even with adjustment screw bottomed out. Checked for vacuum leaks using brake cleaner and noticed no changes too idle. Also has new head gasket, new iac, cleaned throttle body and VAM, new plugs gapped at .32. New wires, cap and rotor. Fuel pressure is 42 vacuum line disconnected. Around 32psi connected.  Disconnecting iac shows no changes too idle, Tps sweep shows no jumps and seems to run smoothly, and replaced vam once before chasing this issue. 

top end issue 
Fuel switch in premium mode, running 93 octane, car does not have any bucking or sputtering, pulls nice and smooth when easing on gas pedal, today i took it for a run after double checking everything (besides getting my high idle figured out) and i decided too see how it acts at full throttle. Car reached about 5500-5700 and a loud pop from exhaust and immediately died, and shut off. (No stutters or anything before i hit 5500) and not even 15 seconds later car starts right up and drove normal even when i slowly got it too 5500 in 1st gear. Seems to only happen with full throttle. No smoking or overheating. Other then these two issues car seems to run well. Thanks for your response in advance 

[Stinger]

Does it happen to have a non-stock throttle body?

If it idles too fast with the idle screw bottomed out and the IAC unplugged then it is getting extra air from somewhere other than the throttle plate. This means if it's using a stock throttle body then there has to be an air leak somewhere.

The high RPM issue I don't really have an explanation for at the moment. Did it not start for the first 15 seconds or was it just that you didn't attempt to start it for about 15 seconds? Just trying to see if there was a temporary "no start" condition or not.

[jasonsvolmo]

Yes, all stock (for now) was working on getting it in good tune before upgrades. And yeah i just let it coast and looked in the mirror for oil on the ground, didnt see any at all and started it right up.
I suppose it wouldnt hurt too double check lower intake manifold, etc.
is it possible boost gauge is faulty and i overboosted, and knock sensor kicked in?
Will check fuel pressure tomorrow, possibly gap plugs too .30 and go from there. Only thing i can think of is if i do have a vacuum leak, possibly making it run way richer than anticipated causing a large back fire. I would assume car would continue too run after, but we will see.

[Stinger]

The throttle body seals most certainly leak so the engine DOES have vacuum leaks. Those typically aren't nearly bad enough to make it fast idle though. This is why I prefer pressure testing to spraying carb cleaner as pressure testing allows you to do it with the engine off so there is less noise and no rush to track down the leaks.

Knock sensor can't shut down the engine, only retards timing some. There is nothing that's supposed to shut down the engine other than the key switch as it's dangerous (loss of power steering and power brakes).

Rich condition shouldn't shut the engine down either, can pop/backfire but not shut off entirely.

[jasonsvolmo]

Okay so update. Took car for test drive today, after checking bolts on manifold gasket, replaced a few vacuum lines. Checked fuel pressure today under boost
At idle, vacuum disconnected reads 42 psi. On my first attempt at full boost (12 lb boost for test run) the gauge hit about 52 which is a little shy of where i need to be, so i took it for another spin, and fuel pressure at idle jumped too 45, and would not drop or go above even in boost on my 2nd run. Disconnected vacuum line and dropped too 42 again. Any thoughts? Still idling at 1200.

[Stinger]

Sounds like the FPR is malfunctioning (assuming the gauge is good). I'm not sure I've ever seen one stick at a certain pressure and I can't visualize how that would happen without the hose being plugged but if that's what you saw then it must be possible.

[jasonsvolmo]

It is a kirban, i bought it about a month ago from your site, ive heard people never get issues with them so thats strange., i did a few more test runs and the fuel pressure just doesnt wanna move. Any thing else that could cause that?
did about 4 more test runs and very first one, fuel pressure was good at idle, vac disconnected. Stuck at 42-44 the entire time through every pull
Fuel pump has been done within the last 6 months, regulator was the last peice i threw on after november

[Stinger]

Yeah, we've never had any trouble with the Kirban, the one on my car is over 20 years old. I'd question whether the hose has an issue, or whether the gauge is acting funky as an FPR is just a diaphragm and spring inside. There isn't really any way for it to "stick" at a certain pressure other than spring pressure that I can come up with.

Does it drop when you add the hose? Should go from 42 down to mid to low 30's depending on vacuum level.

[jasonsvolmo]

Now that i think of it, the first day i got the regulator on i did have too adjust it alot from the box, about 7-9 turns. And gauge is brand new, reading accurate i suspect.
Fuel pressure does drop when i add the hose, but like i said when i take it for a run it will just stick in the 40s and not move. Does not budge with full boost

[jasonsvolmo]

Last update, put stock fpr on and its building fuel pressure again and not sticking. Still have my 1200 idle but cars running alot better 

[Stinger]

Well, I guess there is a first time for everything. Swapping on the stock one and it fixing the problem is about as definitive as it gets. Can you tell me the last name on your order so I can look up the date and contact Kirban about how warranty claims are handled? Never had to warranty one so I'm not sure the process. I tried to look up your email used on here but didn't get any hits.

[jasonsvolmo]

Should be under olmo i have the order # if that helps

[Stinger]

Here is what Kirban said about the warranty replacement:

They can return it to us and we will send a replacement.
Would just need a copy of their receipt and problem with the unit.

Kirban Performance
529 Hayrooster Road
Kintnersville, PA 18930

If you don't have a copy of your purchase receipt let me know.

[jasonsvolmo]

So we are back again. Before i completely fault the kirban, i decided to do a few test and heres what i found
Fuel pump voltage koeo : 10.5
Fuel pump voltage koer : 12.9
Positive fuel pump wire voltage drop : 1.5 way too high
Alternator running at 14.7 volts
I spliced in a 12 gauge ground too resistor wire when i did fuel pump swap. Added splice into thick black wire that goes to grommet in hatch passenger rear grounded too chassis
Kinda weird the stock fpr works better on, but i dont think my issue is the kirban. Also has new fuel pump relay.
What do you think about these numbers? Surely a voltage drop of 1.5 would effect fuel pressure im assuming, ill also assume the fuel pump should run at the same voltage as the alternator. Could be wrong.

[Stinger]

Ideally the pump should be getting full alternator voltage for maximum output. That won't happen with stock wiring though. Have to upgrade the wiring like outlined in our FAQ section for full voltage.

With that said, a 255lph pump shouldn't have any problem keeping up with the fuel demand of your engine even at 12.9 volts. It also can't cause the pressure to "stick" at a certain pressure, though I can't mentally figure out how a regulator can make that happen either.