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Many will change parts until they usually find something.
I had a self-defrosting refrigerator/freezer that the freezer was icing over. A 'parts changer' type came out from the local HVAC company and didn't have any diagnosis, was just going to change every easily changeable part and if that accidentally cured the problem for $200+ I would have a refrigerator worth $75 on the used market...
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Discussion Starter #42
Time to bust out some tools and get to testing

Keep track of results . Write stuff down for reference.
Hey man here’s what I got so far. All the connections and checks with the voltmeter seem good. I think it’s fuel pressure, i connected a Pressure gauge and the initial prime is at about 59-60, so that’s good and it hits there every time so it’s pretty consistent. When running it’s about 51-53psi, according to the book, that’s good. Once I shut down the engine though it says no more than 5 psi drop in 5 minutes, well I had 25psi and roughly 2
Minutes or less. So I’m thinking, since there aren’t any visible leaks, either fuel pump, fuel pressure regulate, or spider?....what do you think?

I’m also thinking that since I’m not getting a misfire, that maybe I can rule out the spider?? Just a guess...?
 

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Fuel pressure regulator and spider are both under the upper intake. Regulator is cheaper than the spider, but what if you have to take it apart twice? You could try them separate or just do it all while you are in there.
Also you can check the pump itself from under the truck. I usually put just a plain rubber fuel like onto my gauge, and check it somewhere near the filter. This is free, so you can try it first. But in the end its probably the regulator leaking down...
 

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Discussion Starter #44
Fuel pressure regulator and spider are both under the upper intake. Regulator is cheaper than the spider, but what if you have to take it apart twice? You could try them separate or just do it all while you are in there.
Also you can check the pump itself from under the truck. I usually put just a plain rubber fuel like onto my gauge, and check it somewhere near the filter. This is free, so you can try it first. But in the end its probably the regulator leaking down...
I was thinking if I have to change the regulator I’m just going to eat the bucks and buy the spider to. It’s a good chunk but it beats doing all that again one day and the spider already had 205,000 on it.
 

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Cam . The situation you described fit a faulty check valve in the fuel pump.

This would allow pressure to bleed back into the tank, and ultimately ,on a warmed up engine , cause the fuel line to go dry. Leaving only the fuel at the spider.

Then when restart is tried, the pump pressures up the system, but has a huge air pocket, however makes pressure nonetheless . That pressures the fuel laying in the spider and the truck starts, but then immediately dies because the vapor in the line ,under pressure has reached the spider, and has to bleed out the injectors and the return system. Enough vapor passes through the injector to stall the engine, and bleed the vapor off , then eventually pushing fuel back into the spider and to the tnk Via the return system.

This would set a p1351 because the Electronic spark timing would be active and the engine would be lower than 250 rpm because of the stall.

Remember when I said "the conditions for setting the code" ? Spark timing enabled less than 250 rpm , at the same time.
Curis was right when he said the early OBD II Computers were "Dumb"

They are.
 

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Discussion Starter #46
Cam . The situation you described fit a faulty check valve in the fuel pump.

This would allow pressure to bleed back into the tank, and ultimately ,on a warmed up engine , cause the fuel line to go dry. Leaving only the fuel at the spider.

Then when restart is tried, the pump pressures up the system, but has a huge air pocket, however makes pressure nonetheless . That pressures the fuel laying in the spider and the truck starts, but then immediately dies because the vapor in the line ,under pressure has reached the spider, and has to bleed out the injectors and the return system. Enough vapor passes through the injector to stall the engine, and bleed the vapor off , then eventually pushing fuel back into the spider and to the tnk Via the return system.

This would set a p1351 because the Electronic spark timing would be active and the engine would be lower than 250 rpm because of the stall.

Remember when I said "the conditions for setting the code" ? Spark timing enabled less than 250 rpm , at the same time.
Curis was right when he said the early OBD II Computers were "Dumb"

They are.

So I just got done changing the pump and I started that thing many times trying to make that light come on. Couldn’t get it. So I’d say it’s fixed......kinda. I still have too much bleeding off but it’s way better than before. I have a regulator, and a spider. Weighing on if I should just change the regulator or go ahead and change both since I’ll have everything undone.....the
Spider is just so expensive though.
 

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Fuel pressure regulator and spider are both under the upper intake. Regulator is cheaper than the spider, but what if you have to take it apart twice? You could try them separate or just do it all while you are in there.
Also you can check the pump itself from under the truck. I usually put just a plain rubber fuel like onto my gauge, and check it somewhere near the filter. This is free, so you can try it first. But in the end its probably the regulator leaking down...
Most Likely NOT the regulator. Blocking the return line (deadheading ) the system and pressuring it up will reveal the answer. If the return line is blocked and the pressure bleeds off, then the check valve is bad in the pump.

Another way to look at it is if you pressure the system , and have a valve installed between the engine and the pump, you can shut of the truck, then close the valve,this would isolate the pump from the system so you can check the function of the regulator.
 

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Discussion Starter #48
Cam . The situation you described fit a faulty check valve in the fuel pump.

This would allow pressure to bleed back into the tank, and ultimately ,on a warmed up engine , cause the fuel line to go dry. Leaving only the fuel at the spider.

Then when restart is tried, the pump pressures up the system, but has a huge air pocket, however makes pressure nonetheless . That pressures the fuel laying in the spider and the truck starts, but then immediately dies because the vapor in the line ,under pressure has reached the spider, and has to bleed out the injectors and the return system. Enough vapor passes through the injector to stall the engine, and bleed the vapor off , then eventually pushing fuel back into the spider and to the tnk Via the return system.

This would set a p1351 because the Electronic spark timing would be active and the engine would be lower than 250 rpm because of the stall.

Remember when I said "the conditions for setting the code" ? Spark timing enabled less than 250 rpm , at the same time.
Curis was right when he said the early OBD II Computers were "Dumb"

They are.
The pump looked like the original though. And if it wasn’t, it’s been a very long time since it’s been changed.
 

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Discussion Starter #49
Fuel pressure regulator and spider are both under the upper intake. Regulator is cheaper than the spider, but what if you have to take it apart twice? You could try them separate or just do it all while you are in there.
Also you can check the pump itself from under the truck. I usually put just a plain rubber fuel like onto my gauge, and check it somewhere near the filter. This is free, so you can try it first. But in the end its probably the regulator leaking down...
Most Likely NOT the regulator. Blocking the return line (deadheading ) the system and pressuring it up will reveal the answer. If the return line is blocked and the pressure bleeds off, then the check valve is bad in the pump.

Another way to look at it is if you pressure the system , and have a valve installed between the engine and the pump, you can shut of the truck, then close the valve,this would isolate the pump from the system so you can check the function of the regulator.
So what’s the chances that maybe I have some slightly leaking injectors then?
 

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Most Likely NOT the regulator. Blocking the return line (deadheading ) the system and pressuring it up will reveal the answer. If the return line is blocked and the pressure bleeds off, then the check valve is bad in the pump.

Another way to look at it is if you pressure the system , and have a valve installed between the engine and the pump, you can shut of the truck, then close the valve,this would isolate the pump from the system so you can check the function of the regulator.
The valve will hold the pressure (like the pump check valve should) and will reaveal any trouble at the injectors or regulator.

By valving the system at certain points you can isolate the problem without any dissassembly
 

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Discussion Starter #51
Most Likely NOT the regulator. Blocking the return line (deadheading ) the system and pressuring it up will reveal the answer. If the return line is blocked and the pressure bleeds off, then the check valve is bad in the pump.

Another way to look at it is if you pressure the system , and have a valve installed between the engine and the pump, you can shut of the truck, then close the valve,this would isolate the pump from the system so you can check the function of the regulator.
The valve will hold the pressure (like the pump check valve should) and will reaveal any trouble at the injectors or regulator.

By valving the system at certain points you can isolate the problem without any dissassembly
okay that’s what I’ll do. I’ll find one that I can install permanently in the hard line for future checks.
 

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I dont think you need to put a valve in for future operations.

But its good you grasp the reasoning and logic behind isolating parts of the system from the other for diagnostic purposes by using a valve
 

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Also , since you have changed the pump, check the pressure on the system again, with the gauge.See if the bleed down time is better or closer to correct.

That will tell you something
 

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Discussion Starter #54
Also , since you have changed the pump, check the pressure on the system again, with the gauge.See if the bleed down time is better or closer to correct.

That will tell you something

Oh I did! It’s ways better! It’s still technically out of limits which is way i was saying maybe my Regulator is bad so it’s it’s old. Not sure though.
 

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And just because a pump is new doesnt mean its perfect.
Also it could be leaking at the connections for the pump to the housing/sender.

That is where valving different places in the system can really shine through when it comes to nailing this crap down.,
 

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Discussion Starter #56
Okay so I think it ended up being a combination of problems . Like the spider and fuel pump. So the both got changed. I would have just done the regulator first but since the new spider came with one and since the truck didnt have the newer version of the spider I went ahead and changed it. And that thing cranks like a champ now. Literally bump the start and it fires up. Also I went and head pulled the lower intake off to also and cleaned the hell out of the ports. I’m going to attach some pictures but it’s looked like sludge built up in the ports. Possible from the the PCV valve I found with electrical tape around it. I don’t know why someone would do that.
 

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Discussion Starter #57
<img src="http://www.hotrodders.com/forum/images/smilies/rolleyes.gif" border="0" alt="" title="roll eyes" class="inlineimg" /> At least they're better than VAG. Any ECM that monitors radios and seat heaters needs to die.
Design engineers need something to do, ya know...<img src="http://www.hotrodders.com/forum/images/smilies/wink.gif" border="0" alt="" title="Wink" class="inlineimg" />
Doesn't really narrow things down.

Codes are set after a certain threshold. If it reads a few voltage spikes it could be a blip in a reading and it would ignore it. After two or three blips, it sets a Pending code which just means that the code is stored, but it hasn't turned on the light yet. Then maybe after 5 logs of that high voltage it will turn the light on.

Then if the light goes away, it means that the condition hasn't been seen for a while. It depends on the system. In your case, it might go away after 15 more times that it hasn't seen the high voltage issue. In the case of an O2 sensor with a higher resolution, it might be 13,000 cycles that it doesn't report the condition before the light goes off.... which could be 10 minutes.
Many will change parts until they usually find something. My son is a mechanic and often gets jobs from other shops. His approach is similar to a criminal profiler. Give what is known to be facts without giving your opinions. He also has dealt with a lot of new, but bad parts and sensors. Corroded connections, bad grounds, voltage, chaffed wires, bad insulation from being probed and subsequently shorting or corroding are often things he finds often. The "Code is always right" gets expensive and change parts. Check basics.
Many will change parts until they usually find something.
I had a self-defrosting refrigerator/freezer that the freezer was icing over. A 'parts changer' type came out from the local HVAC company and didn't have any diagnosis, was just going to change every easily changeable part and if that accidentally cured the problem for $200+ I would have a refrigerator worth $75 on the used market...
see above .....
 

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Wow. Glad I revisited the thread. I havent been here much lately. I am glad you nailed it down.

Like Curtis said OBD 1 is real dumb....

OBD2 is a LOT better.
 
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