Ok, so some back story first: got this 99 Yukon auto 4x back in February. Since I've had it replaced upper intake, lower intake gaskets with the good metal ones, upgraded to the new mfi spider. New egr valve, delco distributor, delco cap and button, delco wires and platinum plugs. New fuel filter, New fuel pump, New coil and ignition module, New cats, k and n air filter. By the way I used dashcommand to install the dizzy, got it set in at 0.6 degrees. So at this point truck runs great and life is good. Drove the truck around town for couple weeks no issues. Took it on a 500 mile round trip no problems. So me and the fam decide to take a week long trip to south Carolina. Half way there the fun starts, cruising at 75mph on I85 truck just dies, no spitting or sputtering just shuts off. Upon inspection I find the fuel pump relay extremely hot and no gas present at the fuel line fitting: FML. found a guy to put a new one in for $400 total. Only brand the local stores had is airtex, had no choice there. Anyway fuel pump installed truck is running again, but now I'm getting p0172 and p0175, system rich on banks 1 and 2 WTF. Truck has a slight stumble and miss at idle, and occasional back fire at highway speeds. Not sure what to do at this point, went to a local orileys and dropped $300 on all new ignition components and fuel pressure tester. So far replaced the coil, idle seems better but still have both the rich condition codes. Will be throwing parts at it tomorrow. If anyone has any ideas on this one I would really appreciate it. About at my wits end with this truck, really debating going back to my expedition if I can't make this truck reliable, oh forgot to add I did a compression test on it when I got the truck: 7 cylinders came out at 195 and number 3 cylinder came out at 190. Sucks rocks to be far away from all my tools and have to deal with this kinda mess, any ideas or input would be awesome.
odd problem, long ways from home.
- Thread starter ASHTEK
- Start date
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BRUTUS_T_HOG
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Smell inside the intake. If it smells strongly like fuel the fuel pressure regulator on the spider has failed.
Will try that first thing tomorrow, should be able to tell by holding the throttle body open with the key on right, and of course the intake tubing removed. Was really hoping that is not the issue as it is pretty much brand new also, the new mfi spider came with one. If that is the issue would a standard replacement for that truck work or do I need to mention the upgraded spider at the parts store?
So I put my fuel pressure tester on this morning. Key on it pegs 100 psi, then very slowly creeps down. I do get a fuel smell in the intake. So now I'm wondering if it will do any good for me to change the fpr with the pressure that high, thinking it might blow out the new regulator too.
BRUTUS_T_HOG
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A standard fuel pressure regulator will fit. I would suspect the 100psi reading is either a low quality gauge or the FPR is stuck closed. With the intake smelling like fuel we know there is something leaking so you'll have to shine a light and check if you can actually see the FPR drip. Either way it sounds like the upper intake needs to be removed.
Could be the gauge, it's a Bosch I picked up at orileys. Got the intake off, only found a noticible clean spot under the fpr. New one installed. Truck runs better at idle and doesn't stumble as bad, but still throwing system rich codes.
Phone Man
Full Access Member
100psi is way too high. Key on should be 60-65 psi...running should be around 55.
