Long start???

[Desert_Rat]

I have a 93 cherokee 4.0 HO that takes 5-10 seconds of cranking before it will turn over.........what could cause that.....Thanks for your advice

[Joopin]

I would put in a new coil, distributor, plugs, wires, and rotor... if that doesn't help, the starter may be on it's death bed... or perhaps its the battery.

[judge09]

That seems like alot to start with. Take joopin's list and start replacing those items starting with the cheapest. If it gets better than your problem is solved. Plugs and wires are always a good start.

[MudderChuck]

I´d check the distributor cap, plugs and normal tune up items.
If that doesn´t do it, a fuel pressure leak down test. If the fuel rail is loosing pressure, the motor gets hard to start. There is a ball check valve in the fuel pump, that lets the pressure bleed off and causes hard starts. Fuel pump is expensive, BMW has a kit 14 9 068 988, to take care of the same problem, for under $10.

[Desert_Rat]

I have already replaced everything that is included in a normal tuneup except for the plugs....which I planned on doing this weekend....I just thought that there might be something that I was missing like the fuel pressure. The fuel pump and filter are ok...this I know because I was the sorry SOB that had to replace them after we bought it last year and it started to die on me and the wife when we drove it....that turned out to be a CPS....so the moral of that story is........Ask the people who know before you spend an assload of money on a 12.00 problem......Thanks for all your guys' advice you are always helpfull.

	Crank position sensor A crank sensor is a component used in an internal combustion engine to monitor the position or rotational speed of the crankshaft. This information is used by engine management systems to control ignition system timing and other engine parameters. Before electronic crank sensors were available, the distributor would have to be manually adjusted to a timing mark on the engine.

[XJNick]

Hi,

I too would look into it being a fuel system pressure problem. The fuel rail is supposed to stay under pressure, even when the jeep is off. It is possible you've got a leak (maybe the injectors) which is removing the pressure from the system, and thus you have to crank it longer while fuel pressure builds back up.

After the jeep has sat for awhile (maybe overnight), punch in the Schrader valve on the fuel rail (cover it with a rag) and see if there is still pressure at the rail.

-Nick

[90Xjay]

I know a brilliant fellow who operates an independent garage in my town. He specializes in fuel injection systems. When I was doing my exhaust manifold, I took my fuel rail to him to have it checked before I re-installed it. He told me that he had a contract for several years servicing a fleet of 25 vehicles with the same 4.0 inline six. We discussed long start cycles and while fuel pressure must build before it will start, he claims that minor timing chain wear with higher miles is the problem alot of times. He has a method of clocking the distributor cap slightly to compensate. The problem is that the rotor is throwing spark just forward or behind the metal contacts inside the cap. The timing chains are so strong they rarely need replaced. But his method makes sense and he worked on a whole fleet of 4.0's for over 5 years. Just food for thought.
BTW< my 1990 with 150K usually cranks for about 2.5-3 seconds before it starts.

Good luck!

[MudderChuck]

I´ve seen timing chain wear and the play in the distributor gears, cause some cross fire (wierd misses and pops). Could also probably affect starts.
5-6 second starts (or longer) have usually been helped with fresh tune up parts, but most times it was marginal pressure, in the fuel rail after a half hour or so of sitting. The pressure can leak down through the ball check valve, the fuel regulator (on the early models) or at an injector.
I most times, eyeball the spark, should be sharp and mostly blue, when a spark plug cable is held to ground with a bolte stuck in the spark plug boot (a rubber glove recomended).
A timing light, moved from plug cable, to plug cable, shining the light on a dark part of the motor, will show up missfires and weak igniton pulse pretty quick.