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86 2.8 tbi, running problem stalls on takeoff! Has been replaced: fuel pump, filter, rebuilt regulator whole new distributor new plugs gaped, new wires new timing chain new vacuum hoses. Hasn’t been replaced ,fuel injectors, ecm what else could it possibly be need help please TIA
 

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Awww..you ain't got shit!
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clogged cat? Bad EGR? Any codes?
 

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86 2.8 tbi, running problem stalls on takeoff! Has been replaced: fuel pump, filter, rebuilt regulator whole new distributor new plugs gaped, new wires new timing chain new vacuum hoses. Hasn’t been replaced ,fuel injectors, ecm what else could it possibly be need help please TIA
Man I have the same problem with my 86 s15 jimmy I just don’t want to buy a ecm and it doesn’t change
 

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Verify injectors are working properly (nice cone and no drips)
Vacuum leak?
How are your power brakes working? Brake booster diaphragm failure can cause massive vacuum leak.
What is the fuel pressure?
Check temp senser. (2 wire one)
When you set timing did you reconnect the distributor electronic advance wire when you finished?
 

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Well I haven’t checked the brake booster or the wire for the distributor but I have found that the oil pressure switch or oil sending units have been melted and tied up so I have recently found that my model and engine has a one,two, and three prong sensors or units. I did some research and explains why my oil pressure gauge isn’t working and I read that one of those activate the fuel pump so I went to a pick and pull and seen a couple of 86 blazers 2.8 to see how there sensors are placed and I cut the wiring harness out so I’m gonna do this and see if it changes my rough starting and rough take off. But I could use some help which sensors do I install. All three? Or just the two prong and the three prong? I know ones for the indicator (oil light) ones for the gauge and one is for the fuel pump control but have no idea which one is which
 

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Yep, I would say you found the problem. I think single wire one is for s10's that dont have gauges.
 

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Ok So the oil pressure relay is for the 4.3 or the carb model before 86 I think because mine senders are located next to the oil filter anyways can you send more pics of that wiring diagram so I can understand how my 2.8 works and also do I hook up all three senders? Because I found a Tee at the junkyard where I can connect the two prong and single prong on one port and the port below can be the three prong
 

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That diagram is specific to 2.8l tbi 1986. dont worry about the relay just hook up the senders by the wire colors. the 2 wire one Is for the fuel pump. Too my knowledge you only hook up 2 of the 3 sendors depending on if you have a oil pressure guage (use 3 wire) or just the idiot light on the dash (1 wire)
 

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Funny thing is I hooked up a 2 plug one already and it still has problems starting also the gauge is still out plugged in or not makes no difference that’s why im curious if the 3 plug sender makes the difference and is it possible that for example my gauges are not working it’s telling the computer that there’s no oil pressure there fore the fuel pump cuts off as the safety feature to save the engine? I have yet to re splice the harness and buy a three prong sensor for now it’s the slightly melted 2 prong plug connected to a brand new sender unit only
 

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If you have the 2 wire one setup correctly the fuel pump will switch on when you get oil pressure. if it wasn't already turned on by the fuel pump relay. If you short the 2 wires you can switch on the fuel pump to test. it is backup for the fuel pump relay . the 3 wire one (large black sender) is for both the guage and the idiot light. The ecm does not monitor oil pressure. make sure none of the wires are fused together or grounded out. Its also possible you have multiple problems. Those wires usually only get melted if the motor has been replaced and everything was not routed as it was originally. A sloppy engine swap can leave all sorts of wiring problems. Headers can do it too as it was in my case.
in my experience lean conditions are usually bad injector(s) or low fuel pressure m. when you replaced the vac lines did you make sure everything stayed plugged in to the correct ports on the tbi?

Where is @oldeerslayer anyway? He has probably diagnosed this issue a dozen times before.
 

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Ok that may have been my problem the 2 prong plug was the only plug still intact and still had good power going through the plug but the other 4 wires were twisted and taped together
 

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4 wires? should only be 3 others , Tan,black,brown. the tan and brown do connect to together on the same terminal. What other wire is in the mix?
 

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The other oil sending unit wires anyways the other wires that were tapped together I separated them and tapped them individually my oil pressure gauge activated and shot to 80 and stuck there with the check gauge light on so I disconnected the negative on the battery to see if it would reset or change I put it back and started it again the gauge and light is still at 80 and check gauge is still on
 

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without the sender hooked up it will either be 0 or 80 depending on if its shorted or not. Either way doesn't matter if they are just the oil sender wires. I am just concerned about that 4th wire.
 

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Ok so there’s a total of 6 wires 2 for the two prong plug 3 for the 3 prong plug and 1 for the single prong plug but I bought the thing without senders and they had threaded plugs where the units thread in well for the wires it was zip tied up with the two prong plug still connected and little melted looks like it had touched the exhaust and the rest of the connectors were cut off and tapped together
 
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