fuel compression & spark, no start..

[TajMan]

Hey guys! I've got a 92 Ram 50 2.4L, had a broken timing belt and has been off the road over 2 years.

Replaced the timing and balance shaft belts, got all the marks right-on. Cranking the engine over now, it has compression we measured (between 90 and 120 all).

It will not run, at first it wanted to pop one time but then never fired since. Backfired once. It has spark.. was suspicious distributor may be 180 degrees off, tried it both ways and still nothing. Fuel tank was drained, and line off the fuel rail the bad gas was flushed out of the main lines.

So stumped. With compression, and spark (tested in multiple positions), and with starter fluid (should fire even if fuel injectors were clogged).. it should fire over but it won't at all! New spark plugs.

and help?

[geezer101]

Hi and welcome to mightyram. So...if you're 100% sure the timing marks are correct, the engine hasn't suffered from bent valves as a result of the blown belt and you have both fuel and spark - it has to be ignition related. You have to put the engine into tune/diagnostic mode to accept any changes to ignition timing or it'll do weird stuff (like - not run...or run like a 3 legged donkey at best). The ECU's in them also suffer from capacitor failures - a common fault. If you can't get it to accept a new tune setting open up the ECU and look for bulging capacitors and any signs of damage to the component side of the circuit board, as this is a fairly accurate indication there's something wrong with it.

[TajMan]

Ok.. I just thought the ECU only controls fuel, and the ignition [is] distributor and I checked and all 4 wires are sparking. Shouldn't the engine at least try and fire off of starter fluid? With the plugs pulled and cranking the motor there is an air/fuel mixture coming out of the spark plug holes, I know fuel pump is working and am pretty confident fuel injectors are firing.

Isn't the '92 2.4 SOHC engine.. an 8-valve engine and non-interference.. and doesn't the positive compression check I've performed tend to agree with that assumption?

[royster]

Do make sure the distributor wires are in correct order...a simple thing to overlook, but would certainly cause problems.

[TajMan]

This car suffered a timing belt failure.. which confused me when I took off the upper timing belt cover the first time, because the belt was still on and tight! After we took off belts/pulleys and the lower timing cover, we found the old timing belt's teeth around the crankshaft gears were shredded off the belt.

This was a running truck until the timing belt failure! The distributor/connections/plug wires hadn't even been touched. This is why we're so stumped and can't figure out why it isn't firing. It is sparking. New timing and balance shaft belts were installed, I took out the 14mm bolt plug on the side of the block and inserted screwdriver to make sure left side balance shaft was correct.. with all timing marks lined up, they all lined up again after (4 I believe) crankshaft rotations. Doesn't the compression check we've performed with a gauge confirm timing is on (or at least close enough to fire) with 90psi+ compression?

[tortron]

you might want to double check the timing, have seen pullys with marks in the wrong places and replacement belts with them in different places. just check with a thumb over the plug hole for compression stroke and keep an eye on the rockers

[Andy 2]

Are you sure you're not getting too much fuel? Or not enough air?

[TajMan]

I'm pretty sure now, that injectors are stuck open! Too much fuel!
Just gotta remove upper intake then fuel rail, and clean injectors minimum.

They look like they have blue tops.. these 2.4 injectors aren't the same as dsm 450CC bluetops ARE THEY!? (I've got like 10 of those on my shelf)

[Andy 2]

Rock Auto has them for $23 each, and there are pictures. They have new and re-manufactured.

[TajMan]

cool,
they're bluetops but much smaller than DSM 450cc bluetops..

[LSR Mike]

the Truck injectors are 275 CC's, the 450's are for Turbo 4G63's. the ECU is calibrated for the 275's you would get way too much fuel. Also , the trucks 275CC injectors are High Impedance and the 450's are low impedance, so they wouldn't work in the fuel injector circuit. 2 reasons why the 450's cannot be swapped in. bummer for sure...