Strange problem with vortec swap (1 Viewer)

[papagyo]

Hi all,

Wondering if anyone has come across this issue after their vortec swap. When starting truck either cold or hot i turn the key and hear fuel pump run for 3 secs then go to start it and it kicks right over and goes to approx 1k rpm then dies instantly. Repeat procedure and truck starts fine and runs without a hitch. This has only developed in the last couple weeks after approx 1k trouble free miles. Motor is a 2004 5.3 using a trickflow fuel pump TFS-25004P followed by a WIX 33737 fuel filter with return line back to tank. Fuel is supplied from new outlet installed near bottom on side of tank and return line goes into the top of tank. I am going to put a pressure gauge onthe fuel rail to see if it stays at 60psi first and then go from there. Any ideas would be greatly appreciated.

Brian

 

[papagyo]

Update,

Went out this morning and no start at all, fuel pump is working engine just spins over like it is not getting fuel.

Brian

 

[Callahan Offroad]

How many miles were on the truck engine you put in?

Is the ecu grounded properly?

 

[papagyo]

Callahan,

60k miles on the engine...this came from reputable source (BD Turnkey) and what exactly do you mean by ECU grounded? I did just a few days ago change out the ECU because BD sent me one with different program (different shift points), I did see that the install person had the ECU mounted on the firewall passenger side and had small rubber standoffs between it an the fire wall. Are you saying that the ECU box itself has to be really grounded?

Brian

 

[Elbert]

any changes to vehicle from when it last ran correctly as far as modifications, changes to hardware & settings...etc

 

[papagyo]

Absolutely no changes in hardware or settings since it ran perfect, as stated above I did change the ECU but the problem existed before this change so I don't believe it was that. The ECU was changed solely to have different shift points.

Brian

 

[NCFJ]

I won't ask a bunch of questions just suggestions.

Check for power at the coil harness to main harness connector, If good there check for spark. Check for fuel pressure at the fuel rail. If that is good pull a fuel rail up including injectors and see if they are working. If you have issues with any of this start back tracing. May sound obvious but check all the fuses related to the motor running and make sure the power sources to the harness are good.

 

[Elbert]

check fuel pressure #1 issue to verify its good, any small variation in fuel pressure can be a problem.

 

[Callahan Offroad]

Start with the fuel like they said, but usually (not always) ecus are grounded to the chassis and sometimes the ground connection goes bad. This happens in volvo and Hondas frequently. The bolts to the chassis are the connection between the ecu box and the grounding. Now I'm not super familiar with GM ECU's but this could be what is happening. Check all power supplying plugs in the truck too. Do you have an obd2 scanner?

 

[djawahir]

I chased a bad MAP sensor for 6 months until I posted a scan of my HP Tuners ignition sequence online. The symptoms for me though would be that the car would crank...tumble like it was going to start...then die. A bad map sensor would shut down the fuel spray immediately after startup. My MAP sensor failed within the specifications and never threw a code....which was part of the reason it took so long for me to find the error. Good luck! Maybe post a video of what's going on? And OBD2 scan?

 

[papagyo]

Did you mean MAP sensor or MAF sensor? This engine has no MAF sensor on it, I will do the scan once I verify correct duel pressure. Your problem sounds a lot like mine was a week ago.

Brian

 

[2mountainfish]

Hello: The check valve on the fuel pump could be bad. Hook up fuel pressure gage and watch for pressure to drop after pump shuts off. If the check valve is bad, fuel will bleed back to the tank. When you start it it will run on the fuel in the rail and then die waiting for fuel to get back up to the rail from the tank. Hope this helps.

 

[djawahir]

Brian, I meant MAP sensor. It manages air/fuel ratio if I remember correctly. I think the sequence is that the pump is primed and injectors spray at key in ON position. At key in CRANK position, the MAP checks air pressure and calculates the amount of fuel to continue spraying from injectors. When my MAP was bad, the engine would turn over and start to run on its own (due to the initial fuel spray in the chamber) and then die (due to the lack of fuel and thus, wrong air/fuel ratio).
If you can hook up something like HP Tuners and chart air pressure against time, you can see if there is an error. For me, my air pressure reading was a flat line...meaning that my MAP sensor wasn't doing anything.

I don't want you to have to go out and buy a bunch of stuff, but if you can find a tuning shop or someone that can come by and hook your OBD2 to a laptop and read stuff visually, it could help you figure out what is wrong, especially if your engine PCM isn't throwing any codes at you.

Good luck!

 

[djawahir]

I also like what 2mountainfish said about checking fuel pressure and seeing how long it holds after pump is primed. I think with the WIX regulator/filter you have installed, you should be seeing about 58psi at the fuel rail engine port valve thingamadoohickey.

 

[Callahan Offroad]

Seriously though get an obd2 scan tool, we invented on board diagnostic tools so we no longer have to consult the ouiji board of guessing what is wrong. There are some sweet ones out there that just pop into the port and connect via blue-tooth to a smart phone. Bullydog makes some, do does Diablo Sport. Your local auto parts store should have a couple of cheapy cheapos you can use.

 

[papagyo]

Update,

Thanks for all the suggestions, problem was indeed the fuel pump. Even though it sounded normal the first time I cycled the key and primed the pump I read 10PSI on the gauge I then cycled the key about about 5 more times and the final time the pump sounded different and it went to 59psi. truck started but this behavior is intermittent with the pump going up and down in pressure. I am replacing the Trickflow TFS25004P with a bosch and at the same time will replace the wix 33737 and clean prefilter. This should (fingers crossed take care of the problem).


Brian

 

[Elbert]

walbro fuel pump has served me well (external model)

 

[ander42b]

Papagyo,

I have be following your thread here. I though I was the only one having troubles with the 5.3 Vortec swap. Did swapping out the the fuel solve all of your problems????

Also the engine I see you got your engine and wiring harness from BD turnkey engine. How was dealing with BD turnkey??? We're they straight and honest??? What was the cost of the engine and the wiring hardness????? Post some pictures of your engine.

 

[papagyo]

Ander42b,

I am still working on the fuel pump swap out.......metric fittings for the Bosch are impossible to find where I live and I have had to order them. I also ordered a new fuel filter as I think the small earls type filter (40 microns) might be restricting things a bit...not sure. The fuel tank was changed from a '62 tank to a '60 tank and a new outlet was put in near the bottom of the tank and is strictly gravity through the filter to the pump. I went with a 100 micron KRC prefilter instead before the pump and then the wix 33737 after the pump with short return line back to tank...hope it all works.

BD Turnkey was awsome to deal with, the motor arrived and was very clean with the harness already on it (that is included in the price), fuse block too. Very simple to hookup to the 4L60E and just maybe 5 wires to deal with. I do not have a need for A/C so I did not hook any of that up although it is all there. Went with a mechanical clutch fan from the original motor and it stays at 180 all day long. I did not like the shift points he programmed in it so he sent a new one out to me and said try it for a few weeks and send which ever one I did not like back, really nice to deal with. Cost for the engine was $2900 to my door.

Brian

 

[papagyo]

ander45b,

Some photos: