Hi Scotty, I love the show and channel! I have an issue I can’t seem to figure out and am trying to do it without shotgunning parts. I have a ‘08 F150 with a 4.6L. It had a blown intake manifold gasket that was flooding a couple of the driver side plugs and causing a misfire with code. I labeled all my wires first then tore it down. The job was pretty easy, cleaned the top of the block well and put it all back together. After that it would crank with no start. I first checked for anything disconnected, 3 times, and everything seems to be together and tight. I then checked the COPs for spark with a light and that was good. First shotgun, changed the crankshaft position sensor cause I figured no power was getting to the injectors then. No change. Got smart and light tested the injectors, they have power. Pulled the plugs themselves to see if I could smell gas or that and I can (not sure if that really means their getting fuel or not, but I could smell it) checked the gap and then did a spark test with the COP on each. All good there. For the fuel system, I started at the fuses, checked the inertia switch, the fuel driver and have power going to the pump. I also bypassed the driver and hear the pump humming. Back at the injectors themselves there’s no Schrader valve which floors me so I’m not sure how to pressure test it, but I do have fuel at the sensor on the passenger side. Oh I also changed the fuel filter and did turn the key on to see if I had any flow before putting it back together which I did. It’s got a full tank of gas also. Things I have changed were both the crank and cam position sensors, the pcvs and hoses, and the canister purge valve, I think it’s called? It was cracked for some reason. What would you recommend I check next and how would you fuel pressure test this?
Hi! Welcome to the group!
Great work with your car there, a ton of work.
I would suggest someone checking your ECU? Sometimes if batteries are fine and everything, you can try to have a trusted electrician or technician check it? It would just be a wild guess. Because most of the time, the not so obvious is what it is.
But getting through basics would be ideal, check the batteries, starters and everything that would make the car start.
Hi Joshua, thanks for reaching out! Is there a good test for the ECU? I have no codes currently.
Since it ran before you did the repair, and it wouldn't start after it, I'm going to assume it has something to do with the reassembly of some components, particularly the electric ones.
If it happened after you tore out a lot of wiring, I would go through and check that all. You said you labeled your wires, make sure they're all in the right location with wiring diagrams. Mistakes happen.
If you're worried about fuel pressure, I would get some Prestone starting fluid and spray it in the intake and see if it cranks up. If it runs on the starting fluid, you would then know it has something to do with the fuel system.
That was my first guess. I’ve checked they multiple times, tested and have voltage from all the leads. I pulse tested the injectors, all the COPs and even pulled the plugs to spark test. All the grounds are good and tight also. Verified all that again yesterday. Tested my inputs to the ECM and they all seem to be working. With that said, if I was to have a vacuum leak, it would start but run lean, right? No start on the starter fluid either. I tested the battery yesterday and it’s showing a bit over 12v cold. Also just to see, I pulled the fuel pressure sensor and dried out the port, turned the key to see if it would fill and it did. Not sure if that’s an accurate test for anything, but I know the pump works because it can hear it, have seen fuel come from it when I took the filter off and now that it’s filling the rails.
Back to the drawing board. Checked all my harnesses, electrical and everything is working and pulsating as it should. I finally got and did a compression test and have low compression in both banks. So I believe that’s my missing side of my triangle. I know I need to remove and look at the intake manifold gasket again as something must not be set correctly. I’ll write my results in a few days.