Sniper Conversion - 72 FJ40 - F155 Engine (1 Viewer)

[WildernessRimFab]

Set up up the wires with a GM alternator plug with a locking tab. Had to consider pump clocking to locate the external fittings appropriately.

After that it was time to primer/paint the tank. It was 40 degrees and sunny so this is the best we got for a Montana paint booth in February. It's drying in the heated garage now.

 

[WildernessRimFab]

Waiting on paint to dry and some more 6 AN line/fittings. Need to finish final fuel pump wiring terminations also when the tank is installed. Otherwise ready for a test fire. Fingers crossed I haven't messed anything up so far as far as I can tell...

 

[WildernessRimFab]

Last step before I button up the tank will be to rinse the tank with a gallon of WD40 and a big magnet stuck to the bottom. I vacuumed it out already but there is some super fine stuff that the shop vac doesn't pick up. The WD40/magnet method is recommended by the pump manufacturer (Tanks inc).

 

[middlecalf]

So the stuff gets suspended in the WD40, then when it’s draining the magnet collects the stuff near the drain hole, right? Then what do you do to get the stuff all the way out?

 

[B y r o n]

Don't waste the gallon of WD-40, just rinse with water drain and let air dry and you'll be fine. If you are trying to get rid of a little rust then let tank sit with Evapo-Rust for awhile and then rinse with water and air dry.

See post #34 in this thread to see what I had to clean out. The Evapo-Rust removed it all.

 

[WildernessRimFab]

Then what do you do to get the stuff all the way out?

You just stick the magnet on the bottom of the tank and swish around the WD-40 or water. All of the suspended crap sticks to the magnet. Then you just pull out the magnet with your hand and all of the crap stays on the magnet.

Looks slick in the manufacturers video:


Water is certainly an option, I just cringe at putting water in a brand new gas tank. Probably paranoia on my part but I already bought the WD so I'm going to go with that.

 

[WildernessRimFab]

I cleaned the tank with the WD-40 and magnet method. It worked very well. I kept the same gallon or two of WD in the tank the whole time and removed the magnets about 10 or 15 times for cleaning. I kept putting the magnets in until they came out clean. Cleaning. The magnets worked well with a clean rag first and then a shot of compressed air to get off the super fine stuff.

After that I installed the pump unit and the sender. There isn't much room in between the baffles in the CCOT Snorkel tank, but there is adequate room for both, splitting the difference between the tank drain and the baffles. See the crude photo below with the clocking of the level sender and the pump.

I did one more leak test at 8 psi with the sender and tank flange installed and found no leaks. Note that you need to have the supply, return, and vent lines plugged to do the leak test with soapy water.

 

[WildernessRimFab]

Installed some new strips of closed cell foam tape on the floor and put the tank back in. Finished up the fuel pump wiring and the tank vent plumbing. I looped the tank vent around the filler neck to get some additional height on the line so that it doesn't fill with gas.

Waiting on 10 more feet of AN hose and a couple bulkhead fittings, otherwise this thing may be ready for a test fire tomorrow night.

 

[WildernessRimFab]

The rest of the parts showed up. Finished the fuel system with the bulkhead fittings though the floor. Double checked that all of the AN fittings were tight.

Had a good friend come over to help, we disconnected the supply line to the Sniper and did a couple fuel pump primes into a milk carton to verify fuel flow and to wash out crap from cutting the AN lines with a cutoff wheel.

I turned the key and it started IMMEDIATELY!!!
Idle was high (1500ish) but the instructions say not to touch the idle screw until the engine is up to temp. We messed around with the idle screw eventually and found that the throttle cable was slightly binding and limiting throttle return. Slightly loosed the throttle cable housing and the issue seemed to be resolved.

One other minor issue is that the new sending unit that came with the CCOT Snorkel tank is reading way past full on 6 gallons of gas. I'll swap out the sender from my old tank and see if the issue resolves. I didn't put the seats back in yet so an easy fix.

I did drive around the block a couple times (sitting in a camp chair of course) and it drove great.

Thanks to everyone who has posted up their Sniper installs. I looked at these for a while, made a plan, and my install was relatively painless.

 

[WildernessRimFab]

I started this up again this morning, idle was low (650) and IAC was 100%. Need to dial that in a little bit more (open throttle blades slightly).
We messed with this last night but we were chasing our tails a little bit.

 

[WildernessRimFab]

Still having some minor idle/IAC issues. My throttle was *slightly* sticking open even though TPS read zero. I installed a second return spring that that seemed to fix that issue.

When I set up the IAC (5-8%) per the holley manual at operating temp, it runs great (at operating temp). Then on the next cold restart RPMs are low and IAC is at 100%...thinking that I just need to get this all buttoned up and start driving it so it can complete "learning"

Also, air temps are in the 30s so maybe it just needs some time to warm up. I somewhat expected this conversion to start right up and drive perfect like a 90's toyota engine with MPFI, but I am slowly learning that this may not be the case.

Anyone else had this issue with cold starts and a newly installed sniper system?

 

[B y r o n]

When you added the second spring did you also reset the throttle position sensor?

 

[WildernessRimFab]

When you added the second spring did you also reset the throttle position sensor?

The second spring was to return the throttle back to 0%. TPS still reads zero. From what I understand in the sniper instructions, the TPS resets every time you restart the truck after you have it turned off for 5 seconds.

 

[B y r o n]

The second spring was to return the throttle back to 0%. TPS still reads zero. From what I understand in the sniper instructions, the TPS resets every time you restart the truck after you have it turned off for 5 seconds.

Good to know, my Edlebrock EFI setup doesn't do that and needs to be manually reset if changes are made. Sort of like gas peddle sensors.

 

[Skreddy]

I have a low rpm issue on cold starts (below 45 degrees F). I have been tuning it out with mixed success playing with the iac settings. You need to set hot start settings first. I would just manually manipulate the throttle the first 5-10 seconds until it idled where you want and drive it a couple hundred miles to complete the learning, then start changing startup stuff.

 

[WildernessRimFab]

I have a low rpm issue on cold starts (below 45 degrees F). I have been tuning it out with mixed success playing with the iac settings. You need to set hot start settings first. I would just manually manipulate the throttle the first 5-10 seconds until it idled where you want and drive it a couple hundred miles to complete the learning, then start changing startup stuff.

Thanks, that's what I was hoping to hear...drive it for a while. Its certainly not undriveable but it doesn't seem 100% correct.

I'm also going to check my Idle Speed Curve Setting on the handheld. Apparently some Snipers have been shipped out with a wacky value on the coldest part of the curve at -40F. Even if you dont start start/idle at -40F apparently it can throw the software (firmware?) for into a loop.

Idle Speed Curve Settings are well documented here: Solving Holley Sniper High Idle Issues - https://www.efisystempro.com/efi-pro-hangout/holley-sniper-installation-startup-troubleshooting

 

[WildernessRimFab]

I verified that my Idle Speed Curve Settings are correct.
I ramped up my fuel prime from 100% to 140%.
Now it idles at 850 on cold startup and ramps down to 750 when warm.

I'm done messing with any more settings until I reinstall the seats and get some driving/self learning.

 

[aztoyman]

Thanks for posting this. I'm considering a Sniper system on my daughter's car. This helps.

 

[EricG]

Thanks for posting this. I'm considering a Sniper system on my daughter's car. This helps.

Agree - I'm just starting to think about this also. And therefore, maybe this dumb question.

Aren't there external (out of tank) high pressure fuel pumps available that wouldn't require the level of modification you've done to your tank? What's the advantage of the in-tank pump?

 

[WildernessRimFab]

@EricG there are absolutely external high pressure pumps. Not a dumb question at all.
There are pros and and cons to both, in my opinion:

External Pump Pros: Easier installation and replacement, lower cost
External Pump Cons: More noise, accelerated wear from heat (not surrounded in fuel), potential fuel starvation when cornering/off-camber due to the limited baffling of the OEM tank.

Internal Pump Pros: lower noise, constant pump cooling due to fuel submersion, less starvation issues due to the in tank reservoir tray (constantly fed by fuel return), one hole in the tank which covers supply/return/vent lines.
Internal Pump Cons: lots of extra installation work, welding on a gas tank, additional cost of pump assembly and recess plate.

Nearly every modern factory vehicle has an in tank pump, so surely there is some reasoning behind that.
(Since this is ih8mud, this is where someone posts up an odd modern production vehicle with an external EFI pump...)