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Engine will not start after sending unit and pump replacement


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Today I tried to start my truck after replacing almost everything from the fuel filter backwards. I filled up the tank with about 4 gallons of gas total. 1.5 gallons was from the old comanche tank, and that gas was quite old, I think I had filled it up in September 2022. I had it running on that gas very shortly during march. The other 2.5 gallons of gas was newer from a Cherokee tank that had been sitting since around march. I primed the fuel pump twice by switching the key to on. When I turned the key to start, the engine started turn over but would continue to do so and not start. My REM read 8.9 volts as the engine attempted to turn over. I got my multimeter and tested the battery twice, on reading before I cranked it again was 12 volts and the one after a second attempt was 11.7 volts. I'm pretty sure I matched the 3/8s and 5/16ths lines correctly when reattaching everything, but if I'm correct if I had misplaced the fuel lines the truck would not turn over at all? Maybe I'm wrong and need to check that again. The pump I bought was not the carter brand but the 1050039 Brute Power brand from rock auto. I don't think the brand new pump should be an issue though. Additionally, the engine was making an intermittent ticking sound every 7 seconds after turning the engine off, which I attached a video of. Do I need to just add more gas or get newer gas? I have about 7.5 gallons left of the Cherokee gas I can put in before I need to go to the pump.

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... if I had misplaced the fuel lines the truck would not turn over at all?

 

Fuel has nothing to do with whether or not en engine will turn over. "Turn over" means when you engage the starter, the engine rotates. It doesn't mean it starts.

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4 hours ago, cruiser54 said:

take the cap off and press on the schrader valve. Like a tire valve.

I've sprayed the valve cap with pb blaster 3 times and freeze off, the thing will not move whatsoever. Pliers won't grip and neither will my pipe wrench, granted it's a harbor freight one. However, there is definitely fuel leaving the tank, as the line going to the filter leaked fuel when I disconnected it. Will go back out to try and get the cap off in a few mins.

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For one thing, PB Blaster ain't that great. Freeze-Off is a superior product. 

Disconnect the hose at the exit of the filter and see what you have. PRESSURE is most important. 

This could be as simple as the rubber hose on the new pump in the tank is bad or loose. 

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42 minutes ago, cruiser54 said:

For one thing, PB Blaster ain't that great. Freeze-Off is a superior product. 

Disconnect the hose at the exit of the filter and see what you have. PRESSURE is most important. 

This could be as simple as the rubber hose on the new pump in the tank is bad or loose. 

Alright so I got the cap off. When I first removed the cap and pressed the pin inwards, no fuel leaked out. I got a pressure gauge from AutoZone and attached it to the valve and turned the key to the on position. The fuel pressure barely made it to 10 PSI, and within 40 seconds it had dropped to about 5 PSI. I cranked the engine for a couple of seconds and the PSI struggled to reach 20, where it then rapidly lost pressure after letting go of the key. Its worth noting that I've never done a fuel pressure test before, so maybe the reading was inaccurate. I simply twisted the brass cap at the gauge end onto the Schrader valve. Fuel is definitely getting to the rail, as when I removed the gauge fuel started squirting out and I had to throw a towel under the valve.  I have not messed with the fuel pressure regulator or anything else on the rail or in the engine bay. The only component I did NOT change out was the fuel filter. 

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I’ll second the fuel filter. 
4 gallons should be enough to run the engine, assuming you’ve got good seals on the pickup side and the fuel line connecting the pump to the sending unit isn’t leaking. 
 

You might want to toss that battery on a charger, too. A fully charged battery sits around 12.6V, if it’s down to 12.0 it’s around 25% state of charge. If it’s still got enough juice to crank the engine over its probably not that big a deal, but a fully charged battery shouldn’t be dropping below 9.5 volts during cranking. Can’t speak for the Renix specifically, but not all ECUs are going to be happy getting less than 9 volts. 

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On 5/30/2023 at 7:46 PM, gogmorgo said:

I’ll second the fuel filter. 
4 gallons should be enough to run the engine, assuming you’ve got good seals on the pickup side and the fuel line connecting the pump to the sending unit isn’t leaking. 
 

You might want to toss that battery on a charger, too. A fully charged battery sits around 12.6V, if it’s down to 12.0 it’s around 25% state of charge. If it’s still got enough juice to crank the engine over its probably not that big a deal, but a fully charged battery shouldn’t be dropping below 9.5 volts during cranking. Can’t speak for the Renix specifically, but not all ECUs are going to be happy getting less than 9 volts. 

Gonna hook my trickle charger up tomorrow. Fuel filter is siting in my garage ready to go, will get replacement rubber hoses tomorrow as the ones connecting to the filter are in pretty bad shape.

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  • 3 weeks later...

Update: I finally got around to putting the new filter in. After charging to 11.97 volts and holding the gas it fired up. Sounded like there was a bit of a knock at first but on the second try it went away. What did not go away however was a hissing noise once started. I have no Idea what it could be, and I don't remember hearing it before this. I have attached a video of it. Additionally, I have put close to 10 gallons in the truck and the needle is still on empty, which is leading me to believe the float is stuck under the filter in the tank. I'll leave it as is for now but does anyone have an idea of what the hissing is?

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10 minutes ago, ratrapp said:

vacuum hose from valve cover to the elbow on the intake is clearly disconnected.

Thought I had always had one that loose. Didn't feel like any pressure was coming out of it when I ran my hand over it. It goes in that rubber bracket to the left of it right?

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  • 4 weeks later...
On 6/19/2023 at 9:36 PM, ratrapp said:

its the back hose off of the valve cover.follow it to the intake beside throttle body elbow and hook it to the elbow on the intake.the elow is where the vacuum is coming from,not the hose end.

Do you have a picture of where its supposed to plug into? Took a quick look under the hood last week but ill have more time to work on the truck this week so I can look closer

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