Got the Whipple and tune all sorted out and the truck is making a bunch of power but I continue to have a nagging problem. Occasionally the truck is difficult to fire up. I will turn the key and it will crank and crank and either barely spring to life (and then transition into a nice even idle) or the start circuit will stop. If that happens, once I turn the key again it fires right up. Other times the truck just fires right up perfectly. The problem seems to be more apparent when it's not on a cold motor (aka I turned it off to go into a shop and come back out and it just cranks and cranks).

Talked to the tuner and he stated that the Crank Fuel and Base Fuel and Base Fuel Table Cold are all stock except for wide open throttle which he states is how they should be. He checked the calibration for the larger injectors and those check out too.

Any ideas or suggestions?

 

Well what's your fuel pump priming pressure at????

 

Is that something I should check in programming or just via my OBDII tool?

 

If you can check with the programmer....I've got a scan tool that I use

 

I have a realtime OBD reader. I will try that. Should I just turn the ignition to on without starting and read the fuel pressure?

 

if nothing works I'd be happy to buy your whipple if there is a good deal

 

Glad you are making good power Radelow. So it sounds like this is a warm start up issue and not a cold start problem. Let me know if I have it backwards.

Try this and report back. Get in the truck as usual. Insert key and turn it as far as possible without starting it. Wait 3-4 secs or about the time you spend putting you're seat belt on. Then continue the key turn to start the motor. Report back if this eliminates the issue. Also report this to your tuner as this would be an indication of fuel pressure not coming up fast enough and tune adjustments could be made.

Other issues could be start up timing or just a dirty fuel filter. I'm also wondering if your TPS sensor may be on it's way out. Just a possibility. Mine started acting strange in the weeks leading up to it's failure.

 

Yes.
Also try noting fuel pressure during one of these start up episodes.

 

Sounds like the check valve is playing up.

Could be a leaky injector. I have one that plays up when the truck is roasting hot (Summer only)

 

Ok here is the video. It is showing AFRP (actual fuel rail pressure). If always drops to below 10 psi when off. This example of hesitation is one of the better ones (ie not that bad). Usually it stumbles for longer or just runs through the start cycle and shuts off the starter. After that if I turn the key it fires right up. It seems like the Fuel Rail is taking too long to build pressure...

Turning the key and leaving for 4-5 seconds does not seem to do anything. You can see that when the door chime starts. It sits on but no fuel pressure builds. FYI I put a brand new fuel pump in when we installed the supercharger.

Also during driving the fuel pressure never waivers from a few psi above and below 40 psi like it should.

VIDEO HERE:

 

I'm betting on the MAF sensor then the tune?

Do you have a custom CAI?

when your engine turns its making the same noise as when I tried putting a smaller CAI I had an issue, engine couldn't breathe properly but was fine after putting back the stock airbox

 

Radelow I would suspect either the new pump has issues or something in the tune is off regarding the fuel pump on start up. Btw what kind of shape is your FPDM in?

I noticed in the video the truck only struggles to start until fuel pressure reaches the mid 30's to 40's which is where the fuel pressure should be but much quicker. The second start up showed the pressure already in the 30's and of course the truck fired right up.

I posted a quick video this morning of mine starting with the fuel pressure display you can compare with.

 

Probably has the original FPDM. Maybe I should start there? It appears to be that fuel pressure is not building quick enough. I would be surprised that a brand new pump from Walbro would have problems...but then again stranger things have happened!!!

I guess i'll start with the FPDM. Probably good to replace since it hasn't been before... I will also change the fuel filter.

 

Good idea. Fuel filter first. Cheapest haha. While your under there have a look at the fpdm. It's back by the spare tire. You probably already know where. Look for corrosion on it. Once unbolted look at the back side as well. Very easy to check and replace for that matter.

 

On it! Thanks guys I will report back. Today I had one of the longer delays to starting and very clearly the fuel pressure was hanging around 10-25 psi before eventually jumping to 50-60 and then back down to 40. Weird.