Thread: Engine Starts then dies after L36 Engine Swap! Help needed!

This is my first Engine Swap and until now I thought I was doing a decent job, but now im lost. For 3 years I have drove my 99 gt to its breaking point the motor was replaced a year ago after I ran it too hot! So I got a 2000 3.8 at a salvage and had a mechanic swap the motors for me everything was great til last winter. Two deer about 2 months apart ran into my drivers side after the second deer I just wired my fender and beat the hood down and drove with a broken headlight.
Recently a mechanic buddy told me he wud trade his 2003 gt that needs a motor for my old 95 jeep cherokee that needs a transfer. And that he wud help swap the motors to boot!
He had told me that the 03 needed a motor cause it had gotten hot while his wife was driving it and ever since never had much power plus it had over 200,000 miles on it! He also thought it might need a fuel pump cause when he wud drive it a couple miles and shut it off he wud have to squirt gas into the Tb for it to start again until it finally just quit on him after driving it 4 or 5 miles.
My wife drives the grand Prix to college so we knew we only had a few days to make the swap we decided the christmas break wud be the best. I followed the billboost write up and we pulled the motor out of the 03 without a hitch and had our sights on the donor motor, after waitng I reluctantly I started without my help thinking he wud show up anytime.... Nope he didnt! I swapped em out myself! I crossed my fingers and the engine started and idled just fine shut it off and tried to start it again but it just cranked. I called it a day the next morning it fired right up I pulled out of the garage got on the highway and when I pressed the accelerator it acted like it was going to die if I let off the gas it leveled out but never got over 20 miles an hr as I returned to garage my thoughts was I need to swap the fuel pumps cuz he was right and there was nothing wrong with mine right?
So here I am my 99 gt was running fine when I pulled the motor and everything is same except the PCM and wiring harness, fuel rail, fuel injectors, fuel lines, and fuel pump. I pulled the fuel pumps and found out that the pump asssemblies from the 99 wasn't the same as the 03 so I took pulled just the fuel pump out of the assembly and tried to modify the pump to use I put it back in the tank and now the Engine will start and die even if I press the gas. I can hear the fuel pump run but its not very loud and I havent put the cover back over the pump yet Sorry for the long message but I wanted to make sure I gave all the info I cud!!

I hope someone can help me soon I havent given up hope yet!

Thank you for your quick responses, I will fill the lim today when I get a ride back to the shop how does the lim affect the engine from starting and staying running?
I did try unhooking the Maf connection last night and tried starting it and it did start and sounded great for a second , but still just died like it wasn't getting any fuel. I pushed the Shrader valve and there was fuel there. I don't have a pressure gauge so not sure what it is, but didnt think that it was anywhere near 40 psi.

After the first test drive, when it wouldn't pick up speed, I would press accelerator and get no response until I let up on the throttle then it just stayed at bout 15 to 20 miles an hour..... Is this the stalling you are referring to?
When I finally made it back to the shop my intial thought was that it wasn't getting enough fuel pressure and thought FPR or fuel pump. Knowing the Original owner suspected a fuel pump problem before the swap I figured he was and still maybe right. I first pulled the FPR off and when I went to remove it it came out in 3 pieces and thought I have to replace it for sure...
Or is this normal and is fine? Cause I cant use the one from the 99 it was to large?
And this part is $60 bucks at Autozone! I did see on Ebay that you can just replace the parts that came off the FPR the bottom o-ring, the fan looking filter thing, and larger O-ring.
So I put it back on the fuel rail hoping thinking it might be OK.
Now I have pulled the Fuel pump from both the 99 and 03 and found out I couldn't just swap pump for pump either! Thought I could just modify the assembly and use the 99 pump/sender unit and lower piece of its assembly and put the 03 top on to it and it would be finally done.... NOPE...The pump/sender unit from the 99 is longer than that of the 03, I couldn't get the top to go down far enough to secure it to the base.I put 2 long zip tie around the unit and put it back into tank replaced the ring and connections. And now the engine starts for a split second and dies it won't stay running even if I pump the pedal or hold it to the floor!
Makes me think that the 03 Fuel pump was in deed the original problem. And my modded 99/03 pump isnt working right either!

Originally Posted by millertime2800

I did try unhooking the Maf connection last night.

I misspoke when I said that I had unhooked the MAF connection. I guess I was mistaken on which sensor was which I unhooked the MAP sensor thinking it was the MAF duh! So as soon as I can get to the car I will hopefully find someone with a fuel pressure guage and test the fuel pressure and try starting it with "The MAF" unplugged this time.

Will the Tb, MAF be the same for both the 00 and the 03 and will the 03 PCM run the 00 Tb and MAF?
Will the PCM from the 99 worrk on the 03?

Sounds good to me 99pgpgt.

Would or could the fuel level sending unit make the engine die? the reason im asking is when I turn the key the fuel level shows full and as soon as it starts the fuel gauge falls to empty as it dies. Can this be the cause of my problem?

Ya that is always my first check because years back I bought a 88 ford truck from a buddy he said it needed a timing chain and wud take a $100 bucks for it so i paid him the $100 and got a timing chain put it on, that wasn't what it needed the front fuel pump went out and the back tank was empty drove that ol truck 2 years.
but I drained all the old gas out of the tank and swapped out fuel filter and blew all the fuel lines out while they were unhooked to ensure that all old gas was out of the lines, and after I put the fuel pump back in, I added 5 gallons then read a post that said it needed 10 gal for the pump to pick it up after its rplaced so then I added another 5 gals so there is at least 10 gal in it.

WoooHoo! I did it! My first Engine swap is done and so far so good!! I purchased a used Fuel Pump off Ebay for $25.00 last friday. After arriving today I put it in and Zoom Zoom purrs like a kitten. Thanks for the advice guys!!

Just want to say I couldn't have done it without your help Billboost! Thanks for everything!!

Great Taste!..... Less Filling!!. Don't drink the Water!!

Next project find a SC and do a Top Swap... More Power....OOHH! OOOHH!

Originally Posted by 99pgpgt

lol you should have just swapped an l67 in it then :P but anyways, good to hear you got it running

The I67 isn't possible right now, but I hope it will be possible sometime in the future though! The 03 gp body was basically free and already had the motor.