Startup hesitation help

[GeauxinUp]

Engine is basically stock for now, other than the 6.4 intake swap. Wanted to try and get this little "issue" ironed out before the headers go on and I get my tune. Since installing the intake, I've developed a slight hesitation on startup after the truck sits for a day or two. I don't daily drive this truck and it often sits for a week or longer without any starts.

I also installed a catch can which I've disconnected (went back to PCV valve) to eliminate that as a problem.

Battery is newish, load tests fine, and I keep it hooked up to a NOCO Genius2D.

I don't have any apparent manifold leaks, and I rechecked all the bolts. When I did the swap, I tested/cleaned the factory injectors and they all looked good. I thought about hooking up a fuel pressure gauge, but see that these trucks don't have any sort of a schrader valve.

I do have a VERY HARD brake pedal when the hesitation occurs. Goes back to normal after startup. If that offers any clue(s).

I do have a CEL for the dumba$$ P0456 (very small evap leak), but I ASSUME that wouldn't have anything to do with this. I plan on either getting it smoke tested, or just tune it out with my HPTuner.

Any ideas for a starting point on what to look for?

Here's the link to the YOUTUBE short to hear what I'm talking about.

 

[rzr6-4]

1) Fuel pump allowing gradual drain back, so it takes a second for the fuel to actually build pressure and start.
---Without the Schrader valve it is a pain to test, but with a few small pieces of hose as adapters I was able to get a tester in line between the supply line and the fuel rail.

2) Parasitic drain or a bad battery could cause you to be down to say 11V after a few days, causing the starter to be a little weak.
---I had a bad battery in my sierra test "good" because after you charged it up it could still discharge well, but if you let it sit all night it would loose all of its charge and be 100% dead in the morning. So even if you test good, I would still be skeptical of it. After a few days of sitting, use a multimeter to check voltage. If you are low I'd check for drain, and if you aren't getting any drain I'd replace the battery.

 

[GeauxinUp]

1) Fuel pump allowing gradual drain back, so it takes a second for the fuel to actually build pressure and start.
---Without the Schrader valve it is a pain to test, but with a few small pieces of hose as adapters I was able to get a tester in line between the supply line and the fuel rail.

2) Parasitic drain or a bad battery could cause you to be down to say 11V after a few days, causing the starter to be a little weak.
---I had a bad battery in my sierra test "good" because after you charged it up it could still discharge well, but if you let it sit all night it would loose all of its charge and be 100% dead in the morning. So even if you test good, I would still be skeptical of it. After a few days of sitting, use a multimeter to check voltage. If you are low I'd check for drain, and if you aren't getting any drain I'd replace the battery.

How did you rig up the fuel pressure gauge??

 

[rzr6-4]

My tester came with this fitting. I needed a female end on one side and male on the other, this fitting is male on both sides for some reason. RED: To splice the male-to-male connection I had some 1/4" rough dia tubing that was perfect to slip over both male ends. BLUE: The other side was male-to-female which I theoretically had the correct end, but the male end fitting was either machined incorrectly or to a different standard so it wouldn't latch into the female fitting, but I had some larger tubing that fit over the large shoulder of the fitting and then over the female connector on the other side as well. Hose clamps on all connections to make sure all was tight. It was super jank but it worked.

 

[GeauxinUp]

My tester came with this fitting. I needed a female end on one side and male on the other, this fitting is male on both sides for some reason. RED: To splice the male-to-male connection I had some 1/4" rough dia tubing that was perfect to slip over both male ends. BLUE: The other side was male-to-female which I theoretically had the correct end, but the male end fitting was either machined incorrectly or to a different standard so it wouldn't latch into the female fitting, but I had some larger tubing that fit over the large shoulder of the fitting and then over the female connector on the other side as well. Hose clamps on all connections to make sure all was tight. It was super jank but it worked.
View attachment 567063

Nice, thanks. I'll see if I can get some time this week to get this rigged up and test it.

 

[jws123]

How did you rig up the fuel pressure gauge??

get the harbor freight fuel pressure tester comes with the correct fittings

Deluxe Fuel Injection Service Kit

Amazing deals on this Service Kit Deluxe Fuel Injection at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

 

[Wild one]

Nice, thanks. I'll see if I can get some time this week to get this rigged up and test it.

If you're doing it like RZR is,hunt up a nitrous fuel rail adapter,it has a male and female end,with usually 1 or 2 1/8" npt fittings.
JWS's kit is far better though

 

[GeauxinUp]

get the harbor freight fuel pressure tester comes with the correct fittings

Deluxe Fuel Injection Service Kit

Amazing deals on this Service Kit Deluxe Fuel Injection at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Awesome. Thanks for the link. Question, I "believe" the pictured part is what I'm needing correct? If so, THIS basic kit includes it?

 

[Wild one]

Awesome. Thanks for the link. Question, I "believe" the pictured part is what I'm needing correct? If so, THIS basic kit includes it?

View attachment 567096

You need a fuel rail adapter with a male and female end,that has 2 male ends.This shows you what you need with the right ends.

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