[Macd7919]

Hey guys, I’m looking for a bit of input from people with similar experiences on a fueling issue I’m having. Once again this car is testing my patience to the max. Here’s a few relevant details on my build:

FordStrokers Dart 363
Custom cam from Woody
11R 190 heads
Billet 7875 Turbo Setup
Glenn’s Performance 1000hp Fox Fuel Kit
- I went with an Holley 525lph pump assembly (complete drop in assembly with billet hanger) instead of the Glenn’s Walbro 450 pump. Lines are -8 supply and -6 return from Glenn’s along with a -12 in/out fuel filter and Glenn’s FPR.
Deka 80lb injectors (authentic, not knockoff stuff)
BBRC Rails
Terminator X for tuning
Fel-Pro MLS head gaskets
92 octane fuel
I have an upgraded alternator and voltage stays steady near 13.6-14.2 volts at rpm.
No leaks have been found or evidence of fuel leaking under pressure.
Feel free to let me know if I left anything else that’s pertinent out.

We were on the dyno tuning the car, data logging each pull, and progressively raising boost via the Hallman manual boost controller. All was well and the car was making solid power. We were nearing our target boost level and at roughly 5500 rpm the head gasket blew with the expected coolant everywhere and billowing white smoke from the exhaust. Based on pulling the plugs it looks like cylinder 5 let go, which is fueled by the first rail on the supply feed from the pump (I feed the driver side rail, from driver to passenger rail, then from back of pass rail to FPR). At the time of the failure the car was making 640whp (5500rpm) and 670wtq (4300rpm) on a Mustang dyno with past runs showing peak hp at 6300rpm so we weren’t even at max power output when it let go. Timing was at 12 degrees and AFR was 11.2-11.5 up to the point where the pressure fell off a cliff. The tuner let off as quickly as possible but the head gasket went almost instantly. We went back and looked at the logs and at the time of failure we were at roughly 16lbs (1-2psi over our target but shouldn’t have been enough to blow the gasket) of boost and injectors were flowing a bit over 500lbh. Fuel pressure was at 60psi and then dropped like a rock to about 40psi (I will confirm exact on data log) and pop went the head gasket. When the fuel pressure started the drop the Holley did try to compensate and the injector rate rose to 80% but it wasn’t enough. Luckily it doesn’t seem like the block was hurt and there is no coolant in the oil.

Everything in the fuel system is brand new and has roughly 200mi on it. The fuel pump is powered by dedicated 10ga power and ground wires and is fused through a 40A circuit breaker. The breaker did not trip. As there are only so many components in the fuel system, I’m leaning towards this being a pump failure to perform in some manner. Maybe it got hot from repeated pulls and couldn’t keep up? Aeromotive specifically tells you to place the return line in the baffle box of the tank where the pickup is, could that have caused aeration and led to a failure? Seems like the car would be using more fuel under boost and returning less? The FPR seemed to be doing its thing as it was seeing 60psi and rising as expected.

Has any one had a similar issue? Are these Holley pumps junk or maybe I just have terrible luck? I had a Aeromotive 340 pump fail on me before (it was just completely dead as where my current pump still primes up to static pressure). I’m frustrated with the car and now I’m going to be replacing head gaskets and I sure as hell don’t want to retain the fuel system as is if it’s insufficient, but I’d also like to not just throw parts at it. Any input would be great from people who have experienced similar issues or if there’s something I’m missing with the fuel system.

Here is a link to the exact pump I’m using:

Holley Sniper 12-347 Holley 525 LPH Fuel Pump Module

This direct fit fuel pump module will drop directly into any 1983-1997 Ford Mustang EFI fuel tank. The module has been designed with a 525 LPH (liters per hour) Holley fuel pump that will support up to 1200 EFI or 1450 Carbureted horsepower (HP Rating @ 60 PSI at 13.5 Volts / 17 AMP Draw) The...

www.holley.com

 

[stangjumper]

Here's my thoughts, don't shoot the messenger.

I think you had detonation.

Hp numbers look inflated for 80lb injectors at 55% DC.

16lbs of boost to much for 92 pump gas, imo.

I don't really care what the a/f on wb said or how little timing you were running. Did he pull a plug between pulls and look to see what the engine wanted?

What plugs are you running?

What are the specs on the cam?

Compression ratio?

What were the coolant and air temps?

What ar on turbo exhaust housing?

What is the exhaust system? Size etc...

 

[Macd7919]

Here's my thoughts, don't shoot the messenger.

I think you had detonation.

Hp numbers look inflated for 80lb injectors at 55% DC. - Those numbers were at the point it went lean, so they will be inflated. I may not have been clear on my initial post, the injectors were at 55% and rising but shot to 80% once fuel pressure started to drop).

16lbs of boost to much for 92 pump gas, imo. Lots of people running 15lbs on my same setup on pump, with appropriate timing. 14 is our target but hard to be exact with a manual boost controller on the initial testing. 1-2psi overshoot could easily happen in winter from a car tuned in summer, and isn’t enough of a overshoot that should make or break a head gasket on this particular setup.

I don't really care what the a/f on wb said or how little timing you were running. Did he pull a plug between pulls and look to see what the engine wanted? Yes, plugs were pulled multiple times between pulls and timing marks checked. All was good. We actually pulled them right before the pull that blew the gasket.

What plugs are you running? Autolite, 2 steps colder than stock

What are the specs on the cam? .577/.579, 112, 236/[email protected]

Compression ratio? 9.5:1

What were the coolant and air temps? Charge temps were around 115-120, coolant temps were around 190. I run a 180 stat and Dual electric fans, car never goes above 200.

What ar on turbo exhaust housing? .96

What is the exhaust system? Size etc...3” downpipe, 3” cutout (not open at the time) full dual 3” back from there with straight through mufflers

Filled in the info you asked for in the quote above. Yes, I’m sure it detonated which is what caused the gasket to go, but we also can see the cause of the detonation on the log was a severe sudden drop in fuel pressure. There’s shouldn’t be a 20psi instant drop in the middle of a pull. It was a sudden drop and not something that was gradually tapering off, basically 60psi then cliff drop down to the 40’s, went lean, and gasket done all in an instant. At least it doesn’t look like the block took any damage so that’s a plus. I updated my post with a bit better info as well on injector flow. I’ll verify tomm when I’m back at the computer but I’m 95% that’s the flow rate we saw. Would it be safe to say this was most likely either a faulty pump/pump that couldn’t keep up? Seems like a pump that couldn’t keep up would be more of a linear drop as rpm rose than a sudden plummet?

 

[Killer95GT302]

Filled in the info you asked for in the quote above. Yes, I’m sure it detonated which is what caused the gasket to go, but we also can see the cause of the detonation on the log was a severe sudden drop in fuel pressure. There’s shouldn’t be a 20psi instant drop in the middle of a pull. It was a sudden drop and not something that was gradually tapering off, basically 60psi then cliff drop down to the 40’s, went lean, and gasket done all in an instant. At least it doesn’t look like the block took any damage so that’s a plus. I updated my post with a bit better info as well on injector flow. I’ll verify tomm when I’m back at the computer but I’m 95% that’s the flow rate we saw. Would it be safe to say this was most likely either a faulty pump/pump that couldn’t keep up? Seems like a pump that couldn’t keep up would be more of a linear drop as rpm rose than a sudden plummet?

Something to cause that sudden of a drop sounds like either the pump suddenly lost power somehow, or maybe your reference line to the regator blew off or cracked.

 

[Macd7919]

Something to cause that sudden of a drop sounds like either the pump suddenly lost power somehow, or maybe your reference line to the regator blew off or cracked.

We checked the lines and they are good, everything is also zip tied at the points of connection for safety. I ran all new silicone lines and used a central vacuum block for the source directly off the manifold. The pump maintained pressure the whole time, it just wasn’t the amount of pressure it was supposed to have. At first I thought we may have tripped the breaker to the pump but when I turned the key to unlock the column to push the car out, the pump primed as normal. The breakers aren’t auto reset style so it would have had power the whole time.I was thinking maybe the pump got hot from multiple pulls or it just gave up the ghost? This is the pump I’m using:

Holley Sniper 12-347 Holley 525 LPH Fuel Pump Module

This direct fit fuel pump module will drop directly into any 1983-1997 Ford Mustang EFI fuel tank. The module has been designed with a 525 LPH (liters per hour) Holley fuel pump that will support up to 1200 EFI or 1450 Carbureted horsepower (HP Rating @ 60 PSI at 13.5 Volts / 17 AMP Draw) The...

www.holley.com

 

[stangjumper]

When my pump ran out of flow, the pressure dropped slowly. It didn't fall off a cliff like yours did.

 

[Killer95GT302]

How much fuel was in the tank? Low enough to start sucking air?

Did you already check the line connecting the outlet of the pump to the hanger feed inside the tank for leaks?

Its possible the pump is the issue but I havent seen it drop off suddenly like that before unless it completely locks up or loses power.

 

[74_5.0L_Z]

Did you verify that the tank fuel level is well above the pickup?

If you are at the hairy edge, you might uncover the pickup under full load.

 

[96pushrod]

Would be good to see the datalog file.

 

[Macd7919]

How much fuel was in the tank? Low enough to start sucking air?

Did you already check the line connecting the outlet of the pump to the hanger feed inside the tank for leaks?

Its possible the pump is the issue but I havent seen it drop off suddenly like that before unless it completely locks up or loses power.

Probably 10-12 gallons in the tank. I haven't dropped the tank yet to get to the pump. There were no external leaks we could find. I'll post a data log below.

 

[Macd7919]

Would be good to see the datalog file.

Just tried to upload one but couldn't find a way to get it to work. It won't recognize the Holley file or a zipped folder. I posted some screenshots below or am happy to upload if someone can tell me the correct method.

 

[Macd7919]

Boost/RPM/FP

 

[Macd7919]

Boost/Fuel Volume at Peak - This I assume is target volume and not actual flow. You can see the fuel pressure has dropped from 62psi to 46psi and is still dropping.

 

[Macd7919]

Boost/Fuel Pressure/AFR - This was at the point the FP started to nose over.

 

[96pushrod]

Just tried to upload one but couldn't find a way to get it to work. It won't recognize the Holley file or a zipped folder. I posted some screenshots below or am happy to upload if someone can tell me the correct method.

I’d probably upload it to a google drive, then set it to public and post the link on here.

 

[Macd7919]

I’d probably upload it to a google drive, then set it to public and post the link on here.

Ok, I’ll see if I can get that going. In the meantime I posted some screenshots above. Let me know if you want to see any other ones.

 

[Killer95GT302]

so that was 17lbs boost, and your fuel pressure dropped over a period of about 2 seconds as RPM climbed - I think you were out of pump.

What did the other runs look like? What is base fuel pressure set at?

 

[96pushrod]

Regardless of what it did on that pull, 17psi of boost at 4300rpm on that pump gas combo isn’t really something I’d try and do. Unless it has a ton of timing knocked out around that area.

It went lean, but it wasn’t ridiculous. However the tuning window on something like that is so incredibly small.

 

[Macd7919]

so that was 17lbs boost, and your fuel pressure dropped over a period of about 2 seconds as RPM climbed - I think you were out of pump.

What did the other runs look like? What is base fuel pressure set at?

Correct, it happened over 1 course of 1.5 seconds on the data log (62psi down to 46psi) so he pulled out of it as fast as possible but 1.5 seconds making a pull is not much time to be scanning gauges. I agree 17lbs is not a target boost to run. I'm on a manual boost controller that appears to be very sensitive, it goes from nearly no change to making large changes quickly once tightened a bit. This was a new build/initial tune so we were slowly adjusting and overboosted about 3psi from what I would expect to see for max boost on the street and pump (I also live in the PNW so temps here don't get that hot like other parts of the country). The other runs were looking good, we periodically pulled plugs to check the timing marks and confirm things were OK. The base fuel pressure is 40-43 psi, would need to confirm on that but I want to say it's 43psi.

 

[Macd7919]

Regardless of what it did on that pull, 17psi of boost at 4300rpm on that pump gas combo isn’t really something I’d try and do. Unless it has a ton of timing knocked out around that area.

It went lean, but it wasn’t ridiculous. However the tuning window on something like that is so incredibly small.

Yes, I agree 17psi is an overshoot but like you said, it shouldn't have been enough to blow some MLS gaskets. Timing was at 12.1 degrees when it went and I'm running a Dual Sync setup so it should have been relatively accurate. I posted the log of that below. To me, and I'm not an expert, this seems like a pump problem. I would have expected the pump to dead head, or gradually drop off as the ramp rate of the injectors seems to be slower than what the fuel pressure drop off was(if the injectors were pulling the rails dry). On the other hand, the pump never shut off or dropped below base pressure once the pull was aborted so not a complete pump failure? That's teh part that has me confused. Maybe the pump got hot? I thought possible aeration in the tank but with more fuel being pulled the return rate should be less if anything... Happy to hear thoughts on it. At this point I'm a bit hesitant to run this pump but the rest of the system seems within reason?