: 4.6 northstar engine



sinclairtay
03-17-04, 12:59 PM
twice i replaced my fuel injector rail on my cadillac engine which is a 4.6 northstar in a 1994 cadillac eldorado and each time i went to start it my intake manifold blew off and the motor caught on fire on top where the manifold was at. do anyone know what caused that and do they think the motor is ruined now. can any other motor go in the car besides a 4.6 northstar.

BeelzeBob
03-17-04, 04:09 PM
twice i replaced my fuel injector rail on my cadillac engine which is a 4.6 northstar in a 1994 cadillac eldorado and each time i went to start it my intake manifold blew off and the motor caught on fire on top where the manifold was at. do anyone know what caused that and do they think the motor is ruined now. can any other motor go in the car besides a 4.6 northstar.

Sounds like there is a fuel leak inside the intake manifold.....????

When the silver top cover is off and the inside of the intake is exposed, have someone turn the key on so the fuel pump runs to pressurize the system. Watch for the leak. Don't start the engine with the cover off, just turn the key to "on" so that that fuel pump runs for a few seconds. Watch the fuel lines, the fitting from the fuel pressure regulator to the return line thru the case of the manifold, the vaccum nipple on the fuel pressure regulator, etc...there shouldn't be any fuel leaking inside the manifold. For it to catch fire there must be a fuel leak in there.

sinclairtay
03-18-04, 11:33 AM
do you think it could be internal? before i replaced the fuel injectors and the fuel rail everything was fine but after i replaced those items twice i started the motor and it caught fire both times. each time like 30 seconds each do you think my motor got to hot either one of the times and it messed my block up or possibly warped a head?
Sounds like there is a fuel leak inside the intake manifold.....????

When the silver top cover is off and the inside of the intake is exposed, have someone turn the key on so the fuel pump runs to pressurize the system. Watch for the leak. Don't start the engine with the cover off, just turn the key to "on" so that that fuel pump runs for a few seconds. Watch the fuel lines, the fitting from the fuel pressure regulator to the return line thru the case of the manifold, the vaccum nipple on the fuel pressure regulator, etc...there shouldn't be any fuel leaking inside the manifold. For it to catch fire there must be a fuel leak in there.

familycruiser
03-18-04, 01:56 PM
Great idea. Also, if there is a fuel leak you will hear the fuel pump cycle on and off as the fuel pressure in the rail drops and rises due to the leak.




Sounds like there is a fuel leak inside the intake manifold.....????

When the silver top cover is off and the inside of the intake is exposed, have someone turn the key on so the fuel pump runs to pressurize the system. Watch for the leak. Don't start the engine with the cover off, just turn the key to "on" so that that fuel pump runs for a few seconds. Watch the fuel lines, the fitting from the fuel pressure regulator to the return line thru the case of the manifold, the vaccum nipple on the fuel pressure regulator, etc...there shouldn't be any fuel leaking inside the manifold. For it to catch fire there must be a fuel leak in there.

Lawrence
03-19-04, 12:00 PM
do you think it could be internal? before i replaced the fuel injectors and the fuel rail everything was fine but after i replaced those items twice i started the motor and it caught fire both times. each time like 30 seconds each do you think my motor got to hot either one of the times and it messed my block up or possibly warped a head?

No that wouldn't hurt the motor. As bbobynski said, you have a fuel leak somewhere and you need to find it. Once you get that fixed it will likely be fine.

BeelzeBob
03-19-04, 12:10 PM
before i replaced the fuel injectors and the fuel rail everything was fine but after i replaced those items twice i started the motor and it caught fire both times. each time like 30 seconds each do you think my motor got to hot either one of the times and it messed my block up or possibly warped a head?



Uhhh.....sounds like something did NOT go back together correctly.

Double check the o-ring seals of the fuel pressure regulator to the manifold case where the fuel return line goes thru the case of the manifold.... Also, double check that the fuel pressure regulator itself is not leaking. Watch the vacuum nipple on the FPR carefully when the system is energized to get the fuel pressure up.

I doubt seriously that anything was warped or hurt. You would have to have a serious vehicle consuming fire to damage the engine or warp anything.....

Just take the silver top cover off and turn the key to on (do not start, just turn the key to on to energize the fuel pump) and the fuel leak should be pretty evident...