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Discussion Starter #1
Sorry, not very knowledgeable so excuse me if this isn't enough a great explanation.


But basically, here is what happends..

When my Bronco (88 351w) has been driving for a bit, 15-20 minutes or so. When I pull up to a stop sign it tries to die on me. The oil pressure gauge drops, then the red Engine light comes on and if I don't hit the gas, it will die.

This only happends after the truck has been running awhile. It can idle for ever perfectly and drives great at all speeds. It only happends when in gear and stopped (or just before while coasting to a stop).

If I throw it back into Park, it will jump right back up and Idle fine..


And again, for the first 15 or 20 minutes of driving around, this doesn't happen at all.. But like clockwork, (or for me a certain point in my 25 minute commute to and from work) it will start doing this.


Got over $3,000 into this darn thing the last couple years and its been a wonderful fishing and snow day driver. But I can't justify dumping the cost of having a mechanic replace the oil pump and from what I've read searching these forums, replacing it myself is out of my skill set.

So I'm just checking in for any other ideas before I throw a first one to come get it can have it sign up on craigslist.


Thanks.
 

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Maybe someone else will chime in but it don't sound like oil pressure to me. You'll lose oil pressure if it's trying to quit. Sounds like maybe a fuel problem. If it was an oil pressure problem it probably would have quit by now.
 

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Discussion Starter #3
Maybe someone else will chime in but it don't sound like oil pressure to me. You'll lose oil pressure if it's trying to quit. Sounds like maybe a fuel problem. If it was an oil pressure problem it probably would have quit by now.


Yeah, I was thinking that.. What's happening first, the engine is trying to die because I'm losing oil pressure or i'm losing oil pressure because it's dying.


I guess I came to the conclusion it was the oil pressure dropping based on the fact I had the fuel pump and fuel tank replaced about a year ago..
 

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Have you pulled in any codes from the truck? It could help narrow down your searching. I agree though, it doesn't sound like oil pressure. The oil pump would be pushing the same amount of oil in P as it would idling in a drive gear. So you putting it in to Park and fixing the problem *should* rule that out.

I just finished with an oil pump install. It was a NIGHTMARE... But if you have enough time, blood to be spilled, and patience it wouldn't be impossible.
 

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Assuming the oil is relativly fresh and correct viscosity and the filter isnt clogging up, and the pick up screen in oil pan isnt pugged up, you might try a more accurate mechanical oil pressure gauge (if you dont have on already) to make sure the pressure is good. Could also be the pressure sending unit malfunctioning.
One test you can do to see if your engine is losing oil pressure due to bearings going is put it in gear, foot on the brake, and give it some throttle. If oil pressure drops its a bad sign. Can you hear any knocking sounds coming from the engine?
 

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pull codes, mine ended up being a few sensors(including O2), Idle air control, and Fuel pressure reg. , still need a tad sensor, but she is getting 13-14mpg and doesn't stall/bouncy idle or have low oil pressure anymore that it had when warm, nor the 6-7mpg

Ive also sea-foamed it, did a tune-up and ran a oil degent additive threw it, but the FPR i think was the main problem, caused the idle to bounce, and i think was thinning the oil dew to unburned gas, all i know is i haven't seen the oil pressure drop or idle bounce since the fuel pressure regulator was replaced, so if mileage is down it be something to look into.

p vs gear is engine under load vs no load so yes it can effect oil pressure, hence why the rpms drop in drive. it was in drive, at a stoplight, warm, my engine oil press. would drop and engine light would come on, but its fixed now
 

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Pull codes. If I read your first post right, something is causing your idle speed to drop when you are sitting there, when it does this the oil pressure also decreases. I am 99% sure yoou do not have a problem with your oil pump.
 

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Discussion Starter #10
Pull codes. If I read your first post right, something is causing your idle speed to drop when you are sitting there, when it does this the oil pressure also decreases. I am 99% sure yoou do not have a problem with your oil pump.

Thanks for the advice everyone. Glad to hear it might be something I can identify..

I pulled codes and got nothing. Of course it wasn't failing at the time and nothing was stored. There has never been more than a brief flash of the Red engine light that disapears the second you hit the gas.

I called a mechanic friend and he told me (and maybe I need a new mechanic friend) all the code would probably say is something like *oil pressure drop to critical* (I'm paraphrasing) and, according to him, we already know that's what's happening. The question is why..

Anyways, I guess I'll need to pull codes again?

Also, to answer the question. It does not do it if sitting in drive with a foot on the break and revving the engine.

It only does it when all three of these factors are present.

1. It's been running for 15-20 minutes.
2. It is in Drive.
3. Foot is off the gas pedal.
 

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Yeah, the drop in oil pressure is a symptom of the problem, not the problem itself...
 

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pull codes go from there. if the oil pump was going bad it would of shit the bed by now.
 
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