Hi, everyone. I have a 2001 XJ sport 4.0L with 150,000 miles on it. I bought it in 2004 with about 50,000 miles on it.

I'm trying to track down and solve a slow-start problem. Up until about 5 months ago, it started pretty much on the first turnover -- that is, I turned the key, and the starter turned the engine over once and it fired right up, hot or cold. Right around September, however, it started taking much longer only when cold -- sometimes 15 or so cranks, often requiring a second starting attempt. And when it did start, it would sputter for a second or two before coming up to normal idle speed. Once it's going, it's smooth and powerful, no problems.

Here's an extra layer of difficulty -- the check engine light has been on for 3 years due to a "evap emissions leak, small." My mechanic is stumped on this, and I've been too cheap to pay dealer prices to track this down, so I unplug the battery for a while to reset the computer prior to it's emissions check every year. The light always comes back on after 50 miles or so.

Back to our cold-start problem -- I did have our mechanic try to solve it last month. He tracked it to a low fuel pressure when cold, which I had previously suspected after experimenting with the schrader valve on the fuel rail (just a few drops when cold, a good spray when hot). Guessing it was the check valve, they replaced the entire fuel pump assembly (with Jeep part). Didn't solve the problem.

So... since then, I'm still reeling from the cost of that project (also had rear main and oil pan gasket done then) and considering where to next throw money at the problem.

The ECU (computer), CPS and TPS have all been replaced within the last 4 years or so. I replaced the plugs about 2 years ago.

My theory is that either a fuel injector (they have never been replaced) is leaking fuel into a cylinder (hence the stumbling startup?) or something involving that evap leak is getting worse, maybe a vaccum leak, and causing fuel pressure to be lost as the engine cools.

Does anyone have any suggestions? Could the evap emissions leak (which has been going on for years) have anything to do with this 5-month-old slow start condition? Or should I have a new set of injectors put in?

 

With a new fuel pump assembly installed and you still having symptoms of extended crank with "stumbling" upon start up, the primary suspect is a leaky fuel injector or injectors.

Here is a possible scenario. Excess fuel leaks into the cylinder from a leaky injector. This results in a drop of fuel pressure. Cranking the engine for an extended period of time eventually builds up enough fuel pressure for the engine to start, but when it does start, the engine "stumbles" as it burns off that extra gasoline.

Here is how I would proceed if this were my vehicle. This procedure will help you isolate exactly WHERE you are losing fuel pressure. You will need a fuel pressure gauge and accessories. You can rent this kit from many big box parts stores, so call around.

Hook up fuel pressure gauge on the schrader valve on the fuel rail

Start engine and bring to normal operating temperature.

Observe test gauge. Normal operating pressure should be 49 psi (plus or minus 5 psi)

Shut engine off.

Pressure should not fall below 30 psi for five minutes.

If pressure falls below 30 psi, it must be determined if a fuel injector, the check valve within the fuel pump module, or a fuel tube/line is leaking. An adaptor tool/hose included with the fuel pressure gauge can help you with this. Consult gauge manual for specific information on this but here is basically how it works:

*Turn the engine off and immediately clamp the fuel line at the adaptor hose. Watch the pressure gauge and see how long it takes to lose pressure.

*If the pressure remains at 49 psi for an extended period of time then the problem is in the tank - possibly the check valve. If the pressure falls below 49 psi fairly rapidly then the problem is most likely a leaky fuel injector. And if they are old injectors with a lot of miles on them, replacing the entire set wouldn't be a bad idea.

Hope this helps. Let us know what you find!