Engine starts then dies

[alaskaviper]

I just had my engine rebuilt and have the howell TBI installed. It is the AMC 258 i6 / 4.2l AMC 258 i6 / 4.2l with DUI and TBI. I have almost 100 miles on the engine since the rebuild. So yesterday I pulled into the drive way to check the fluids and it just died on me. I thought I was out of gas cause I knew I was close to empty. I got five gallons and put it in. Then I tried to start it and it would crank but not turn over. After several tries it would turn over and then die. If I give it gas and hold it at 2000 RPM then it will run for about 10 seconds then dies. I'm getting fuel and have spark. Nothing has changed since i been running it. The distributer is tight so that didn't move. I checked the ground for the computer and they are all tight. The grounds are not painted or rusted. I was thinking fuel pump but now that I can get it to start for a few seconds, I'm not so sure.

I am open to suggestions on what it might be.

And to and to the pain. I got in my TJ to go get gas and ran over a bolt which gave me a flat tire. And somebody stole the bag out of my glovebox that has the lug nut lock key for the spear tire. So I cant change the tire until I get to O'riely to get another key. BAD WEEKEND.

 

[BusaDave9]

We have to narrow down the problem to either gas or spark. Use a spark tester.

Do you have an electric pump? If it is not mounted low enough it may need to be primed. If you ran out of gas there is air in the pump and it may be having trouble sucking gas from the tank.

 

[alaskaviper]

Its n electric fuel pump that came with the Howell tBI kit.

 

[BusaDave9]

Check to see if you are getting fuel and/or use the spark tester to see if you are getting a spark.
To check for fuel disconnect the fuel line from the fuel injection. Hold the fuel line where you won't mind spilling gas. You can use something to catch the gas. Then have someone turn the key to run. You should have a constant stream of gas come out. If not your pump may have lost it's prime.
Do you have compressed air? If so put the air line in the gas tank filler and try to seal it with a rag. Try to blow air into the tank and see if you can force gas out the fuel line that is still disconnected.

 

[alaskaviper]

OK so I pulled the fuel hose off the filter and had the wife crank the engine. I got maybe a few drops to come out. I then checked the wires going to the fuel pump. I then thought I'm replacing the fuel filter so why test it with the old one, so i put the new one on. I also added another 3 gal. of gas. So it was either a loose ground wire at the pump, clogged filter, or low gas (which I dought cause I added 5 gal. then started troubleshooting). So problem is solved now. Thanks for the help.

 

[BusaDave9]

Good to hear you got it going. I am thinking you ran out of gas and the pump lost the prime. At that point there was air in the pump and it couldn't suck gas from the tank. This is a problem with aftermarket electric fuel pumps. They need to be lower than the tank and that's not easy to do. Howell says to mount the pump on the frame rail.

I would be extra careful not to run out of gas. This is one reason new cars have the pump in the gas tank. The downside is it can be a royal PITA if you have to drain and drop the tank to work on the pump.

 

[Purple77CJ7]

I run a Howell TBI on my 401 with the same electric fuel pump. I have lost the prime on the pump. To run it long enough to prime, unhook the harness for the fuel pump relay and use a jumper wire from the power terminal pin to the fuel pump terminal pin. Then you can run pump until it primes. I have had to do that on the trail a time or two from vapor lock.

 

[alaskaviper]

Ok so I have another questin for the guys running a howell TBI kit for a AMC 258 i6 / 4.2l . So I decided to replace the fuel hose while I had it taken apart. and I could not get the 5/16 hose on the barb connector for the TBI. I measured the connector and it had a 3/8 diameter. The I.D. of the connector was 5/16. Now all the hose I took off was 5/16 and that is the size that comes with the kit. The hose looked like the PO forced the hose on, he also didnt follow instructions and put the filter between the pump and TBI. So I'm thinking I will need 3/8 hose from the fuel pump to the TBI but wasn't sure if that would cause problems with going from a smaller hose to a larger one.

 

[alaskaviper]

Ok so heres an update. I'm really looking for any suggestions. So I changed the fuel pump with a new one and filter. Problem is still there. So I dropped the tank and found out I have a factory 20 Gal. poly tank. Anyways I went ahead and changed the fuel sending unit since I had the tank down. And went ahead cleaned it up and made sure it wasn't dirty down there.

So I ran a test and ran a hose to a fuel can and the Jeep fired up and ran fine. OK so I figured something with the tank. Anyways tank is clean and new sending unit. Put it all back together Jeep started fine, I thought I was good and then it died and the problem is still there. I'm out of ideas, Anybody?

 

[Torxhead]

I does sound like you have it narrowed to a fuel delivery problem at least. As I recall, those fuel nipples going to the back of the t.b.i. are metric, but going to a 3/8" fuel line does sound better. So is your fuel tank vent system working properly? If you hear a hiss of air when you remove the fuel tank fill cap that would indicate a problem. Another possibility could be fuel pump operation, are you getting full battery voltage to the pump? The Howell instructions state 10-12 p.s.i. at the t.b.i.

 

[alaskaviper]

well I think I got it figured out. Or atleast the jeep runs and drives for 2 blocks. I will test it tomorrow more. So after checking everything and replacing fuel hose from filter forward, it turns out it was the 3 feet of hardline between the tank and the filter. I knew I should have just replaced it when I had the tank down. Thats OK cause I was able to get my hand in the crack and get the hose off the sending unit. So crossing my fingers problem is solved.