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HELP

C:\Users\T\Pictures\2016-01-24\20160124_110227.jpg

I'm sure this is not good. How do I clean it? Can I use wd40 or just a wire brush?
 
greengiant0311 said:
The oil pressure sensor was the one down by the filter.
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On my 1991 V3500 with TBI, the oil pressure sensor saftey relay is next to (almost under) the distributor. The only sensor I know of down by the oil filter is the Knock Sensor.
 
1-ton said:
On my 1991 V3500 with TBI, the oil pressure sensor saftey relay is next to (almost under) the distributor. The only sensor I know of down by the oil filter is the Knock Sensor.
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unless you meant air filter
 
greengiant0311 said:
Ok so I used my power probe to check pump and pump comes on when it has power. So I disconnected the relay, made a jumper to the hot to fuel pump from battery and have power to pump. Left hot wire in place and it started right away! Where's the problem at? This is the 3rd relay. If I run the wire to bypass the relay I planned on hooking it into the ignition so that the pump comes on when the ignition is turned on and off when the ignition is off. The oil pressure sensor was the one down by the filter.
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You might have replaced the oil pressure sending unit. Sorta bell shaped with a male plug. I have only seen one time where the oil pressure sensor was at the filter. And that was owners choice, not from stock.
 
Well it figures that was the part I asked for and that's what they gave me. So the sensor is up top? Well I think that's the only part I have left to change anyway.LOL
I will replace it this week and let yall know how it goes.

So just to be sure I need the one for the ECM because they asked me if it was for the gauge last time?
 
and fyi for later on down the road .

coolent temp sensor in intake = ecm feed.

coolent temp sensor in left head = gauge feed.

these 2 get mixed up a lot of tbi engines from the same keyboard parts store jockeys .
 
and be extra carefull on the back of intake sensor its in a brass 90* adaptor if I recall . and needs to be held good before you try and remove the sensor or it WILL BREAK off in the block .
 
greengiant0311 said:
Well it figures that was the part I asked for and that's what they gave me. So the sensor is up top? Well I think that's the only part I have left to change anyway.LOL
I will replace it this week and let yall know how it goes.

So just to be sure I need the one for the ECM because they asked me if it was for the gauge last time?
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Are you still talking about the oil pressure one?

If so, you don't need either one. The oil pressure switch is redundant in case of relay failure. You can look at the wiring diagrams if you disagree. Unless it and the relay are dead, the engine will start with either failed. A failed relay will result in delayed starting, that's it. Often cited as taking 10 seconds to start.

Edit: here is the wiring diagram, you can clearly see the oil pressure switch in relation to the relay: https://ck5.com/forums/attachments/eaglemark-gif.138958/
 
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dyeager535 said:
Are you still talking about the oil pressure one?

If so, you don't need either one. The oil pressure switch is redundant in case of relay failure. You can look at the wiring diagrams if you disagree. Unless it and the relay are dead, the engine will start with either failed. A failed relay will result in delayed starting, that's it. Often cited as taking 10 seconds to start.
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That is interesting. So, are you saying that if the fuel pump relay fails, the oil pressure sensor will take over as the fuel pump relay...allowing it to send power to the fuel pump? Also, are you EagleMark on some other web sites...like gearheadEFI.com or ThirdGen.org?
 
1-ton said:
That is interesting. So, are you saying that if the fuel pump relay fails, the oil pressure sensor will take over as the fuel pump relay...allowing it to send power to the fuel pump? Also, are you EagleMark on some other web sites...like gearheadEFI.com or ThirdGen.org?
Click to expand...

Definitely not EagleMark. He was way smarter on this stuff than I.

But yes. The way it is wired up the oil pressure switch is redundant. I can't get to the service manuals in the link in my signature where I am now, but I was able to find someone that posted this:

*** UPDATED BY TSB 893206E, DATED OCTOBER 90

When the key is first turned ON, without the engine running, the control module will turn the fuel pump relay ON for two seconds. This builds up the fuel pressure to normal operating pressure. If the engine is not started within two seconds, the control module will shut the fuel pump OFF and wait until ignition reference pulses are present. As soon as the engine is cranked, the control module turns the relay ON, which powers the fuel pump. The control module continues to power the fuel pump during engine operation. If the fuel pump relay fails, it is backed up by the oil pressure switch, which continues to operate the fuel pump as long as oil pressure remains above 28.0 kPa (4 psi).

I can't verify that TSB, but I know what the manual says. Prolonged cranking to start an engine is a result of fuel pump relay failure. The delay is because it takes longer for the oil pressure to build up and close the switch.

I *have* heard some conflicting results from folks who have disconnected the oil pressure switch. Theoretically GM could have had the ECM use the relay for initial startup, then shut the relay off and use the switch, but it is easily tested by disconnecting the relay then trying to start the vehicle, and then reconnecting the relay and disconnecting the oil pressure switch while it's running. Obviously both components have to work correctly, if they do they vehicle should start and run. I've done it on a TBI and TPI rig, both worked as expected.
 
From all the posts on this I've still not seen the fuel pressure with complete original system hooked up. If the pressure is and remains correct then it is not the pump system. If the pressure is different while hooked to a direct pump bypass then you have unwanted resistance in the system that needs to be addressed.

This is best with the voltage drop test. Ground can be tested with DVOM. Do not use analog meters with computerized systems.

Did you replace the large ground strap from the engine to the body with the engine change, do you have the small strap from the Negative battery cable to the body right by the battery?

Fuel pressure, Fuel pressure, Fuel pressure, it's all about the fuel pressure,
 
greengiant0311 said:
The only code is 1 flash then 2 flashes. From what I've


seen that's normal?


I will check that area today. I didn't notice anything that jumped out at me but ill give it another look
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This code will flash three times after the diagnostic terminal is grounded. any additional trouble codes will show after, so if it shows 12 three times then no codes , then it shows no trouble codes.
 
well. it is still giving me heartburn. I bypassed the relay for the fuel pump and it ran good for about a week. Then it died on me on the way home. I let it sit for a couple of minutes and it started up and I drove the rest of the way home. Started it a couple of weeks ago to move it out of my drive way and it died again. Battery wasn't holding a charge. New battery. Alternator was bad. New alternator. Will start but wont run now. As I was disconnecting battery the NEG cable was hot. Is it a bad ground? I just want to frag the damn thing. But its paid for and has lots of brand new parts. Damn
 
The ground cable shouldn't get hot--that to me,indicates a high resistance..might not hurt to replace it if its original...could be it has only a few strands inside it somewhere making contact,then loses connection when it heats up..

I had a stalling problem on my '72 K5 that came and went I couldn't pin down the cause for a long time--every time I replaced something and it wouldn't stall again for days,I thought I had it licked--then it did it again..this time after it stalled,I could not get the starter to crank,it would just go "clunk",and not spin the engine over..

I finally found the issue--some previous owner must have decided to use a top post battery instead of the original side post type,and they just snipped off the side terminal end off the positive cable and for some unknown reason they spliced about 12" of a top post cable to the original cable,soldered it with plumbing pipe solder and flux,then taped up the splice and shoved it up under the battery tray..

The cables at the splice were just a lump of white corrosion with electrical tape wrapped around them,and you could see only a few strands of good copper remained,the acid core solder and flux ate the copper and turned it to white dust..
I used a jumper cable from the positive battery terminal right to the starter to by-pass the positive cable,and it cranked and fired right up..

The truck never stalled again after I replaced the battery cables..the ground cable evidently had been replaced with a top post type,but they decided to butcher & splice the positive cable...:screwy:
 
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