Okay so I’m stumped. I have a 1987 f250 with a 6.9 idi, I had a issue where it died on me on my way to town, but would start and drive another 3 miles before it would stumble and die again. I thought air intrusion so I replaced all the fuel lines and got rid of the rear tank and selector, also replaced the lift pump with a quality one. Started up and sounds and runs great when it’s cold but right when it warms up, it will idle and do mid rpm great but once you go over probably 2000rpm it starts stumbling and blowing blueish white smoke. Reminder all this started happening randomly one day. I have no idea why but any help would be greatly appreciated.
6.9 idi not running at high rpm
- Thread starter Iditurd
- Start date
Check the fuel pressure would be the first thing I would do. Harbor freight has a tester for $30.00
It has good fuel pressure, just threw a new fuel pump in and have checked and it’s pumping at a good pressure to the ip…
onetonjohn
Full Access Member
Where are you finding quality lift pump? I heard they all where junk. International has one but it's $800, at least that's what came up when I looked last. High pressure injection pump is way higher than 100psi.
onetonjohn
Full Access Member
I think you want a analog gauge that's more like 0 -15psi maybe 10. I think when I'm running, I have like 3psi at idle. Could be wrong but it's low. This is for lift pump at the filter.
onetonjohn
Full Access Member
If you update your signature with your truck details (not sure how I did it) like Franklin2 and I, we may be more helpful. I know it's not sucking oil from the modulator, case vacuum doesn't come from intake, but the blue smoke makes me think burning oil - if it's more white, then coolant or timing? I'm guessing. I'll defer to the experts.
I bought a Carter one, has good reviews and I can confirm it was putting out more pressure that the old one did (ran fine on the old one until now) but I will get a analog gauge as soon as possible
I will try to figure that out… I ain’t so good at technology and yeah I was thinking burning oil… white would mean starvation for fuel i believe but it’s kind of a mix of blue and white. Again this issue only happens when it gets to operating temperature
If you have a regular pressure gauge sitting around, you could rig it in there like I usually do on the fuel injection systems when I test them.
1. Find the schrader valve(looks like tire valve) sticking out at the top of the fuel filter housing. Get a tire valve tool and unscrew the guts out of the valve. Find a rubber hose and hose clamp that will slip up over the schrader valve and tighten the clamp.
2. Get your gauge you found, get fittings to adapt the gauge to the hose with a hose clamp. If you need to check it while driving, you can get a long enough hose to where you can run it through the back of the hood and tape the gauge to the windshield for road tests.
It's the best way to check the pressure. I don't think you need much pressure, the guys on here know what it is, but I think it is between 5-10 psi.
1. Find the schrader valve(looks like tire valve) sticking out at the top of the fuel filter housing. Get a tire valve tool and unscrew the guts out of the valve. Find a rubber hose and hose clamp that will slip up over the schrader valve and tighten the clamp.
2. Get your gauge you found, get fittings to adapt the gauge to the hose with a hose clamp. If you need to check it while driving, you can get a long enough hose to where you can run it through the back of the hood and tape the gauge to the windshield for road tests.
It's the best way to check the pressure. I don't think you need much pressure, the guys on here know what it is, but I think it is between 5-10 psi.
I added an electric fuel pump for extra good measure and I get around 10 psi with no change, right when it gets mid rpm it starts blowing a blueish white smoke and coughing, let off and it idles magnificent. Not burning coolant, I tried pulling oil fill cap off to relieve pressure in crankcase with no avail.
I’m starting to think it’s a issue with the injection pump or injectors
IDIBRONCO
IDIBRONCO
The first thing that I'd recommend is to try advancing your timing to see what happens.
