2005 GT Hard Starting

Apr 18, 2005
83
0
7
Valencia, CA
My 2005 GT is giving me some trouble. When I try to start it, it has to crank over for 3-4 seconds before it fires. And sometimes it just barely starts, then sorta bogs and stumbles for a couple of seconds before it evens out. It used to fire really quickly. The strange thing is that once I start it, if I shut it off and try to re-start, it fires instantly. But if I let it sit for a while, it gives me the hard start issue again.
I thought it was a fuel pump issue, but that doesn't seem to be the problem. (Side note: My stock fuel pump crapped out last year, and I replaced it with aftermarket junk. It works ok, but doesn't draw all the fuel from the passenger side tank, and I stall out with 70 miles until empty showing... but that is a separate issue). I pulled the rear seat, and even pulled the pump out, and it checks out. I've tried turning the key to run for a few seconds before trying to start, to prime the system, but that doesn't help. I've also replaced the fuel filter. Once it is running, there are no issues. I can redline it through the gears and it doesn't run out of fuel or spark.

It is strange that it is hard starting after sitting, but will immediately fire if I shut it off and restart it. Any thoughts? Fuel pressure sensor? Crank position sensor? That FPDM thing in the trunk?

Other possible related facts: 1) I just replaced the Mishimoto radiator. I had one in there and it started leaking, so they replaced it. Could I have damaged something taking it out? 2) I have an Edelbrock supercharger on it.

Thanks!
 
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HemiRick

I'd be looking at jacking under the house
Jun 28, 2020
725
273
73
57
Memphis TN
The fuel system is not holding pressure....when off, it should. there's a check valve in the pump and nothing in the front of it should leak fuel. You prob need a pump.
 

EmmJay

Member
Jun 16, 2019
68
18
18
120
USA
Try cycling the ignition on and off 3-4 times before starting it. Leaving in the on position for about 2-3 seconds each time. The pump shuts off a few seconds after the ignition is switched on. Cycling a bad pump multiple times is needed to get the pressure up to proper levels. Also, you might want to visit this forum: ExplorerForum.com The 2006-2010 V8 models share the 2005-2010 Mustang's 4.6L 3V V8 and there are a lot of threads there about fuel system problems with this engine. I am a long time member having owned Explorers and Mountaineers for over 20 years. The people there are very friendly and knowledgeable.
 
Apr 18, 2005
83
0
7
Valencia, CA
Try cycling the ignition on and off 3-4 times before starting it. Leaving in the on position for about 2-3 seconds each time. The pump shuts off a few seconds after the ignition is switched on. Cycling a bad pump multiple times is needed to get the pressure up to proper levels. Also, you might want to visit this forum: ExplorerForum.com The 2006-2010 V8 models share the 2005-2010 Mustang's 4.6L 3V V8 and there are a lot of threads there about fuel system problems with this engine. I am a long time member having owned Explorers and Mountaineers for over 20 years. The people there are very friendly and knowledgeable.
So I tried cycling like you suggested... and that seemed to work. So that narrows down my problem...
 
Apr 18, 2005
83
0
7
Valencia, CA
The fuel system is not holding pressure....when off, it should. there's a check valve in the pump and nothing in the front of it should leak fuel. You prob need a pump.
Is the check valve inside the pump... or in line? I don't have it in front of me now, but I seem to remember something in one of the corrugated tubes that I assume was a check valve. If that is the case... I kept my original pump. I wonder if I could swap it out...
 

EmmJay

Member
Jun 16, 2019
68
18
18
120
USA
So I tried cycling like you suggested... and that seemed to work. So that narrows down my problem...
Some Explorer/Mountaineer owners have installed a check valve in the fuel line after the pump and before the engine bay. The closer to the pump the better. This holds pressure in the fuel system when the pump is turned off so the pump doesn't have to pressurize the entire fuel system on startup. They do this because it is a fair amount of work to replace the pump in these vehicles.
 
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