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Spark & Fuel but no start

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fuel start
6K views 60 replies 17 participants last post by  loykd 
#1 ·
I've had a lingering problem with starting, which I think has turned into a failure.

Engine is getting fuel. I thought that it might just be flooded, and let it sit overnight. I checked the plugs and they're damp. Scrubbed all the contacts on the spark plugs and replaced.

The plugs are generating a spark.

When cranking the engine, it cranks and occasionally will try to start, but it doesn't "catch". It sounds as if the engine is flooded, but I'm baffled because even after sitting for a day, it didn't start.

Could it be a coil that's not generating a "good" spark?

The ignition module is relatively new, as is the battery.

Any ideas?
 
#4 ·
This sounds like so many V8 no start or nearly starting threads.
In my instance it wasn't until I replaced the distributor cap and rotor that the problem was solved.
Before that we'd replaced the coil, amp etc.
In hindsight while we had a spark, odd voltage readings that we'd recorded, we think, were due to arcing in the cap.
There is truly no substitute for genuine ignition parts.
 
#6 · (Edited)
A little more about the problem:

It started out weeks ago when it would take two turns at the ignition to get it started. 1) Crank for a few seconds, sounding like it wanted to turn over; 2) Crank and it would start

Now, the first start of the day is pretty unreliable, and it seems like it's getting flooded. It'll sputter and sound like it's trying to start, but it never gets there. I can smell the gas, and when I pulled the plugs yesterday, it certainly had gas in the cylinders.

After sitting all day Saturday and half of Sunday, it finally started (and restarted), but this morning, I'm SOL again.

I visually inspected the distributor cap and rotor and both "appear" to be fine. No visible cracks.

How do I diagnose this?
 
#7 ·
You need Fuel / Air and spark to run an engine .. you have spark and fuel so the next thing would be would be do you have fuel and air in the right mix ratio?

Assuming nothing broke and given it was running and now doesn't ... what could possible adjust the air fuel mix ratio, has a history of causing poor running ... yep we have a winner ... AICV.

Call Rovers North and order up genuine AICV ...

Actually don't ( sorry zack ) .. take out your existing one and clean it with carb cleaner and a small brush.
 
#9 ·
Leaky big air hose. If it's original they rot out underneath.
 
#16 · (Edited)
Spark & Fuel but no start

I think you guys are over thinking it, the caps and rotor buttons the first things to go, the rotor button specifically develops a crack in it at the rivet and arc's through the shaft, and bingo no start. It's cheap, you can get it at your local auto parts store as well.
Even new ones
Just be careful pulling it off!


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#17 · (Edited)
The sudden 2nd start try req rings a bell re issues that i had with my RRC - went years & years acting like it could hardly wait for me to come along & turn that key, but then one day it suddenly would usually need 2 tries. Unfortunately, I can't recall at the moment which amongst a few different starting issues ended the always-on-1st-try era. If it has been more than a year or two since you have changed out your spark plug wires, then give that a shot - dielectric grease in the boots might also fix spark wire condition issues. And any undercarriage hits around the time of the onset of your symptoms that could possibly be restricting exhaust flow, including inside your muffler?

Lucas cap & rotor issues always suspect in these re-branding years for those...and if your buying the pure generics, C'MON MAN!!!
 
#18 ·
Spark & Fuel but no start

Lucas and Land Rover rotor buttons are riveted too, and suffer the same failure mode as the rest. The cap is thicker however but that's it. I buy the Lucas stuff normally but they all seem to fail (some within 1000 miles or less), personally had 2 this year and 2 others when I was there did the same thing.


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#19 ·
Agree there is too much analysis going on. Replace cap and rotor. You can't tell if they are bad just by looking. Be sure rotor is pointing at #1 piston at compression stroke.
Be sure there are no vacuum leaks from the small hoses on the intake plenum. Reseat all plug wires in the diz cap and on the plugs. Double check they are run to the proper plug.
 
#21 ·
i would walk backwards along the ignition system
Rotor Button -
Cap - <Check>

loose/bad plug wires - running on 7 or 6 cylinders is entirely doable - the engine will "cough" and you will smell gas in the exhaust

Coil - check for weak/no spark

Amplifier module - they work or don't generally

my 2 cents
 
#22 ·
PO sold my D with the #3 and #7 plug wires crossed. Their mechanic said it was a faulty #7 injector. It still ran at highway speeds, but like a 3-legged dog blowing hydrocarbons.
Let her warm up then measure the temp at each exhaust manifold right at the head. The non or miss-firing cylinder(s) will be apparent. IR temp guns are cheap and should be a staple in your toolbox.
 
#27 ·
you know, i don't actually know the answer to that -

every time - i've thought it was bad, it turned out to be the coil - or the rotor button that was the issue, but if your getting spark to the cylinder at the plugs your cap/rotor is moving it along from the coil.
 
#28 ·
have you looked a the white wire from the coil to the ECU?

It sends a 9v pulse to the ECU to let it know the engine is running. if the ECU doesnt see the signal it won't turn on the fuel relay after the prime cycle.

you should see a pulsing signal if you use a test lamp on pin 39 of the ECU.

Alternatively something like rovergauge will let you know if the relay is powered.
 
#33 ·
If you have a good spark at the plug, I think you can ignore the amplifier module. When you said you're getting fuel, what did you check? Did you disconnect the supply line and turn the ignition to see if fuel sprays out? in that case..If your getting pressure to the rail, one of two things would be logical to check next.. first, fuel pressure regulator. if it's not holding fuel in the rail at a PSI needed, it would explain the rough start, no start, sometimes starts symptoms. Could be the regulator it self or a vaccum leak. Second, the injectors aren't firing which would be electrical but you said the plugs were wet so this isn't likely.

Have you checked the regulator?
 
#34 ·
Did you disconnect the supply line and turn the ignition to see if fuel sprays out? in that case..

first, fuel pressure regulator. if it's not holding fuel in the rail at a PSI needed, it would explain the rough start, no start, sometimes starts symptoms. Could be the regulator it self or a vaccum leak.
Fuel Supply Line: I disconnected the fuel supply line at the rail and fuel sprayed out.

Vacuum: I see only two 1/4" vacuum lines on the engine. One is on the back of the manifold by the stepper motor and the other is on the distributor. Both were replaced. Are there more?

Fuel Pressure Regulator: How do I check that? (and where is it?)
 
#37 · (Edited)
So hopefully someone who's more knowledge then I will chime in on this but here is my understanding on things to check:

The pre 97 engines don't have a valve to connect a fuel pressure gauge so skip the whole "what should the numbers be" piece of of this diagnosis. If the diaphragm was torn or there was an airleak, the spring would hold the valve completely shut and shoot the rail pressure up. Therefore at idle, the injectors would be spraying more fuel than designed and you'd flood the engine. Not 100% sure that would prevent it from starting though( you could probably hold the throttle wide open and crank it to be sure). What's more likely the case (if it's the regulator) based on your description of smelling gas and wet plugs, is the diaphragm has torn and the vaccum line is pulling fuel into the manifold and flooding the engine.

Easiest thing to check would be to pull the vaccum line off the motor and smell it, or rub your fingers around the metal tube where the line connects to see if it's wet or smells of gas. Then you'll know if you're sucking gas into the manifold. If you don't smell anything, next would be to check for a vacuum leak in the housing that you can't see. If you have a longer piece of tube, you can connect it to the regulator and suck on it. If you can pull air it's leaking. If you don't having anything handy you can cannibalize the line from the manifold to the vaccum advance. Third, you can try sucking on the vacuum line while cranking to see if it starts. if it does, then it's not the regulator but you have a vaccum leak in the manifold somewhere.
 
#38 ·
This is really kicking my ass!

It started... for a few days. There were some return problems, like stalling or chugging at lower RPM/higher load, and hard starting, but at least it started. Then those problems cleared, and I thought that somehow, the motor had self-healed. When it ran, I checked and found that there is a vacuum pulling air from the regulator and that the regulator doesn't have any gas in that vacuum line, so I presume that the diaphragm is working ok. Pulling the vacuum hose off the regulator did change the way the engine ran.

To recap, I've changed the spark plug wires, the distro cap, the rotor. I changed the fuel filter about 2k miles ago when I dropped the tank. I replaced the fuel pump then. I replaced both the vacuum line to the pressure regulator and to the distro. I smell fuel when it (tries to) start, and I've previously checked that fuel comes out of the rail.

I get the sense that it's a fuel or air problem and not an electrical problem.

-Where else would there be a vacuum leak?
-Thoughts on replacing the fuel pressure regulator and fuel filter?
-Where else to troubleshoot?

Thanks guys!
 
#40 · (Edited)
Try pulling the return fuel line off the regulator and turning the key on. Fuel should be coming out of the regulator. If not, you either dont have the required 45 psi to your injectors needed for fuel to atomize or the regulator has failed. Smelling fuel doesn't mean the system is working properly.

What condition is your intake hose in ? IE no holes or leaks ?
 
#41 ·
Did you do this ?


have you looked a the white wire from the coil to the ECU?

The chicklet can have a bad connection and in some case fail completely ... mine failed on the way up pikes peak ...

It sends a 9v pulse to the ECU to let it know the engine is running. if the ECU doesnt see the signal it won't turn on the fuel relay after the prime cycle.

you should see a pulsing signal if you use a test lamp on pin 39 of the ECU.

Alternatively something like rovergauge will let you know if the relay is powered.


__________________
 
#43 ·
1. Intake hose is pretty new and in very good shape
2. I checked the white wires off the coil and the connectors are still in good shape
3. I pulled the outlet fuel line from the fuel pressure regulator, and with the engine not running, fuel pump on, fuel comes out of the hose.

And just so I didn't leave any stones unturned, I checked tire pressures and they're good. Ha.

sigh!!
 
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