Wont Start

[explorer98]

So Im updating what I found out with my 5.0 in my 98 Explorer. The number two cylinder had no compression so I torn down the motor and #1 and #2 cylinders got hot and started to melt the pistons. I put 2 new pistons in and replaced the rings. Got it all back together and it tries starting but just back fires. I tried repositioning the Cam sensor and nothing. Im thinking it has something to do with timing but not sure what to do next. Any body got an idea.

 

[black_demon69]

So Im updating what I found out with my 5.0 in my 98 Explorer. The number two cylinder had no compression so I torn down the motor and #1 and #2 cylinders got hot and started to melt the pistons. I put 2 new pistons in and replaced the rings. Got it all back together and it tries starting but just back fires. I tried repositioning the Cam sensor and nothing. Im thinking it has something to do with timing but not sure what to do next. Any body got an idea.

check timing marks on timing chain you could be 180 out
also check firing order

 

[RonD]

I would check firing order on coil packs one more time, yes I know you checked it already, me too, but I still get it reversed, lol

Cam position sensor is for fuel injectors, spark is based on CKP(crank position) sensor, behind the main crank pulley, it isn't adjustable, and if it isn't working then you would have no spark(or fuel) at all.

What happens if you add fuel manually to the intake?
Reads like you have spark
Do you hear the fuel pump come on for 2 seconds when key is turned on?

You can't really setup timing chain 180 out, like a distributor, but if you did remove timing chain and re-installed you could have miss aligned it, but that would usually cause valves to hit pistons which wouldn't sound like a backfire.


Melting pistons is from pre-detonation, pinging/knocking, I assume you could hear this prior to the loss of compression?
So there is an underlying problem that caused this.
Lean fuel mix can cause it, perhaps an intake gasket leak near #1/#2.
Low fuel pressure at #1/#2 injectors
Carbon build up in #1/#2 from running too rich over time, sticking injectors

EGR(exhaust gas recirculation, cools cylinders) system not working, but I would expect all cylinders to show signs of pinging
Too much spark advance, bad ICM(ignition control module) in PCM, but that should have effected all cylinders.
Did any other pistons have pitting from pinging?

 

[explorer98]

All the other pistons looked fine. I just took the timing cover off and every thing was good their. Ive replaced everything electrical on the engine except the crank senor. Should I try that? Not sure what to do next.

 

[RonD]

Have you tried adding fuel to the intake?
Quick Start spray(ether)
Or just put some gas in the intake and crank engine

This will tell you if you have spark and spark at the right time.
So CKP sensor is fine if engine starts.

If engine starts by adding fuel manually and then dies your issue is fuel delivery.
Fuel pump is not coming on, check fuse, relay and then pump itself.

Melted pistons could have been fuel pressure dropping over time causing lean condition which overheats cylinders.

 

[explorer98]

Ok I'll give that a try.

 

[explorer98]

So I looked at the timing chain and it was lined up. Got it back together and it fired up and ran for a couple of min and died. Turned the key over to see if I could hear the fuel pump and nothing. Poped the shrader valve and gas came out but bearley . It just kinda trickled out. So looks like the fuel pump is no good. When I get it changed out I will update this and let you know if that solved my problem. Thanks Ron D.

 

[explorer98]

So I got the new fuel pump in and still wont start. I have fuel all the way up to the pressure regulator and then nothing. I have tried two different PR and that didn't make a diff. Could I have a vacuum leak? Should their be vacuum on the hose when you crank it. Because if I pull it off their is nothing or if I pull the hose off the break booster their is nothing. Im thinking the spacer I have for the intake manifold got hot and warped. Need some input please.

 

[RonD]

No, there is no vacuum until engine is running, above 500 RPM, normal idle is 750 RPM

Do you now hear the fuel pump for 2 seconds when key is turned on?

Crank the engine then pull out an easy to get to spark plug, see if it is wet with fuel, this will tell you if fuel injectors are working.

Dump some gas in the intake and crank engine, if it doesn't fire up then you have no spark.

This is a 1998 Explorer Sport model, so 2 door, right?
1998 4 door explorer had a Type B PATS anti-theft system, not sure on the 2 door models.
Type B PATS disabled fuel injectors and fuel pump but allowed starter motor to crank if engaged, so a no start but it would crank

Ford had other anti-theft systems as well

 

[explorer98]

Every once in a while I can get it to start and run for a few min and then it dies and wont start again. It sounds like it wants to fire but wont.

 

[RonD]

OK, one more time

Have you tried adding gas to the intake??????

If so did it fire up and then die????

Don't care about the new fuel pump and that you have checked for fuel at the rail, have you manually added gas to the intake?

 

[explorer98]

I have tried starting fluid and it did not fire on it. Not even a hiccup.

 

[RonD]

Then focus on spark, that is the problem

Spark starts at the CKP(crankshaft position) sensor behind the main pulley(crankshaft)
Without a Pulse from the CKP sensor the computer won't start the spark(or the fuel injectors)
Crank engine then remove one spark plug and check its tip for fuel, if fuel is there then CKP sensor is fine.

Next in line is the computer(PCM), no way to test these but you can remove connector and check for corrosion, and then pull it out and remove cover, look at circuit board, any damage if usually easy to see, i.e. blacken spots from component burn out.

Coil packs are next, computer grounds these then un-grounds them to fire a spark, just like the old single coils.
You can use an OHM meter to test these, but it will only tell you if a coil is bad, it won't tell you if it is good, lol, but since you have 2 separate coil packs with 2 coils in each the odds are pretty good that the engine would start and run if one coil or a coil pack was bad, it would just run very rough.

Same with bad spark plug wires or spark plugs, wouldn't cause a no start, just rough running.


Do you have an anti-theft system?
A light in the dash board?

 

[explorer98]

The CKP is new and I have pulled the plugs and they are wet. It has the PATS system on it. The PCM is also new. I've replaced about everything on it but the spark plug wires. When ever I get it to fire up it does run rough.

 

[explorer98]

(Update) So I came to the conclusion that im not getting any spark. So I need some advise on were to start because im not familiar with this set up. So if some could point me in the wright direction that would be awesome. Just for a refresher it a 98 ford explorer sport with a 5.0 swap.