[YotaLuver]

I have swapped a 1987 4Runner 22 RE engine (along with the entire harness) into a 1984 4Runner. I now a major glitch and need advice:

I have gas flowing into the engine (manifold, oil pan and everywhere) with the negative battery cable dis-connected. I ran it yesterday and it must be deveolping some kind of back pressure drawing fuel up through the recovery line from the gas tank. Also, what kind of damage is this doing to the interior of the engine. I have drained the oil and am going to let it air out for a day...but, until I can figure this out I really stuck.

Any thoughts would be greatly appreciated.

 

[YotaLuver]

Add'l info

I should have also noted that I swapped out the fuel tank and replaced the main fuel line with the larger '87 OEM line. I am using the return fuel lines from the '84 OEM.

 

[toyomoho]

If the engine is fuel injected, fuel enters the manifold from the fuel injectors or cold start injector. The fuel delivery system is still pressured at engine shut off. The fuel flow from these injectors should be turned off when electric power is off. If one or more injector has poor seal it can leak the pressured fuel into the manifold.

A leaking fuel injector can result in too much fuel in the cylinder and cause hydraulic lock at engine startup and engine damage. Too much fuel also results in excess cylinder wear and is hard on the catalytic converter (if the engine has one).

Might pull the spark plugs after engine shut down and determine which cylinder(s) is still getting fuel. If all the cylinders seem to be getting the same amount of fuel check the cold start injector.

All the injectors can be removed and tested for leaking by redirecting the injector flow into a container, then cranking the engine (pull an ignition component so the plugs will not fire and engine not start).

Suppose it might be possible for the EVAP system to forcing fuel back through the system and into the intake manifold. Can check for this by removing any EVAP vacuum lines that go into the manifold and checking for fuel.