Power Loss at 55 mph

Last night the wife was driving my son's 99 jeep. She was trying to get it ready for him when he comes home on leave. She was doing frwy speeds and she said it lost power. No noise nothing. She stepped on throtle but it did not respond. She tried to start it, it turns but won't light. I had issues years back with my 96 cranking but not lighting. It turned out to be the CPS.. I will check the fuel rail for pressure if there is none I will try ether for a start. If it fires I will check fuel pump and filter. If it does not fire I will check CPS distributor (for rotation and power) ! If you guys have any other suggestions please chime in. Thanks in advance for any similar experienced post!

Sounds like the CPS is the place to start for sure, make sure you replace it with an OEM one.

Mine did that to me a couple of years ago if I went over 75mph. It ended up being a plugged fuel filter.

CPS, check for fuel pressure

Went ahead and replaced CPS with no luck! Checked codes and I had a PO455! I've never heard of this code causing a no start but it won't start so I'm thinking bad fuel pump???

I have not checked fuel pressure but it did squirt when I depressed the schrader valve stem on the rail.

If I remember correctly, shouldn't there be more fuel squirting out than a squirt? I mean it should spray all over? I do not have a gauge, but can I use a tire gauge that threads on to check the pressure?

A final question can the CPS be checked with an ohm meter, if so how?

HELP! The wife's driving my CNG pickup and I'm having to drive my van to work. Even though mileage is the same CNG is only $1.61 and diesel is $3.99. Help!
Thanks in advance!

P0455:

Technical Description: Evaporative Emission Control System Leak Detected (no purge flow or large leak)

What does that mean?
This indicates a fuel vapor leak or lack of purge flow in the EVAP control system. It means a large leak has been detected. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.

Symptoms:
You likely won't notice any drivability problems.

Causes:
A code p0455 most likely means one or more of the following has happened: A loose or improperly affixed gas cap A non-conforming gas cap (i.e. not factory/original brand) Other leak or damaged piece in EVAP system
_____________________________________________

i doubt this is related to your problem.

Boss Cherokee said:

Went ahead and replaced CPS with no luck! Checked codes and I had a PO455! I've never heard of this code causing a no start but it won't start so I'm thinking bad fuel pump???

I have not checked fuel pressure but it did squirt when I depressed the schrader valve stem on the rail.

If I remember correctly, shouldn't there be more fuel squirting out than a squirt? I mean it should spray all over? I do not have a gauge, but can I use a tire gauge that threads on to check the pressure?

A final question can the CPS be checked with an ohm meter, if so how?

HELP! The wife's driving my CNG pickup and I'm having to drive my van to work. Even though mileage is the same CNG is only $1.61 and diesel is $3.99. Help!
Thanks in advance!

Click to expand...

Remove the gas cap and see if it starts.

A defective gas cap is the first thing to check on the P0445 diagnostics list.

regarding the CPS, what brand is it? Those can fail right out of the box if its one of the autozone / advance cheapies

Yup did the auto zone O Reileys was next day. I know about the evap system. I was aware of all the particular such as gas cap pump Excetra my question regarding that was can it cause a no start? Thank you for that info Grimm.I will return the CPS ând tell them it was the wrong one because of the prongs. But my main question is can the CPS be checked with an ohm meter off the vehicle? Second question can the P 0455 code cause the no start due to shuting fuel pump off? I still have not determined if I have enough rail pressure? I crank the motor over to try to get rail pressure but I don't know if the pump is working or the CPU is sending a signal to the fuel pump. I checked voltage with pump disconnected and have 11.38 volts in one prong (tan blks line wire) but when hooked up it drops to 1 volt. Can I jump the fuel pump to see if it works without causing damage?

The fuel rail will prime when you turn the key to the run position, the pump fires up for a couple of seconds. The fuel pump relay won't close again to supply full and constant pressure until the PCM gets a few good pulse signals from the CPS.

An ohm meter test on the CPS can be an iffy thing, if it tests bad it is bad, but if it tests good it may still be bad.

The ASD relay has to close while the engine is turning over and the fuel pump relay has to close. If they both close while cranking and you get a no start, it is most likely a component that is bad, fuel pump, coil etc. If they don't close while you are cranking it is most likely a motor management problem, sensor or power supply.

I usually lay finger on the relay while cranking, you can usually (sometimes) feel when they close. Kind of a hit or miss way to troubleshoot, but it often works for me. The click when the relay closes is subtle, it may be hard to recognize the first few times.

Ok. I forgot to mention yesterday I switched starter relay and fuel pump relay and cranked motor. To check fuel pump relay. It worked. He engine cranked but again no start , so I know both pump and starter relays are good. Next test. While cranking should'tt the fuel rail come up to full pressure of 47 -51 psi?? I will also check the pressure gauge on my 96 to make sure gauge is working properly.
I will also exchange CPS for a o reileys to cancel out CPS as the cause! I also noticed the evaporator pump runs with ignition on so I know it is working. I just don't know if it should run continuously or shut off when a certain pressure in the system is reached?

Fuel pressure good! Maybe it is a bad CPS so I will return the Auto Zone crap and go to Borg Warner sensor and see what happens!

Update for those interested! Ran checks on all sensors. Cleaned connectors with contact cleaner. Bought a new CPS from DEALER and installed. Ran a spark test because I got a couple of back fires. The arch was very weak! Pulled the coil and installed a wheeling spare off my 96 shazaam! Took the Borg Warner coil back lifetime warranty and installed it and she is running like normal. No Evap code came back nothing good to go! Thanks to all that showed interest in helping. I hope this helps others and those that chimed in!

2nd Update! Started having start and stall issues on my 99 4.0 auto a week after my coil and CPS replacement! I had checked TPS MAS and other sensor connections when I did the CPS. The TPS showed low voltage signal but I decided to wait after replacing the CPS whether I was going to replace the TPS or not. I had charged my battery because of excessive cranking so everything worked fine after the coil and CPS replacement. Then a week later had hard starts and I had to step on the throttle for it to idle after 10 or so seconds it would idle fine. I had suspicion that the battery was going bad and sure enough it was bad!
The point I'm trying to make is that, although a fully charged battery may seem fine, replacing it can be all you need, even though my CPS was bad! When you start trying to diagnose problems check the condition of the battery 1st, especially if it is a few years old!hasta

Also, don't forget to check connections to the battery... Some years ago I got stuck in denver for 2 weeks when my problem was the wires inside the battery terminal (the ones that connect the clamp to the wiring harness) had corroded and were making a bad connection.

BulletMaker said:

Also, don't forget to check connections to the battery... Some years ago I got stuck in denver for 2 weeks when my problem was the wires inside the battery terminal (the ones that connect the clamp to the wiring harness) had corroded and were making a bad connection.

Click to expand...

I just went through pretty much the same thing with my 96. I didn't notice any problem until I had to run a bunch of short errands. I started and stopped maybe 6-7 times in a short period of time and then the inside light dimmed and the solenoid chattered on the 8th or 9th start/try. When I finally got a jump start, the radio lost it's programming and the motor ran really bad for a minute or so. Next morning I went to start and the motor ran like the CPS was on it's last legs or the MAP was toast, as soon as the voltage stabilized everything was OK again.

Voltage tested 13.2 after sitting all night, but the starter turned over slower and slower during most every start for the next couple of days. It took a load test to know for sure, I had a dead cell in the battery. Which really sucked because the battery was two months out of warranty, no telling how long it was sitting on the shelf at the auto parts store.

Point is, the starter sucks a lot of amperage and if it sucks the system down far enough it seems to mess with the PCM programming and/or throws sensors out of range.

It's pays to suspect the battery, it may save you throwing cash at unnecessary sensors.

The P codes and the MIL codes are just an indicator, most times they just pop a code because a sensor is out of range. It may be out of range because that sensor is bad, it may be out of range because the voltage for the whole system is low or some connection has high resistance.

Yes sir! An older battery will be my 1st suspect from now on. All these tree hugger restrictions on manufacturing is really raining down on hard on manufacturers and it's trickling down to us on price and quality!!! I HATE buying Chinese but our government is out of control on restrictions to manufacturers, and then they up the import tax on us trying to bleed out two nickels! Check that ring blood out of a $10.00!

another thing to consider is when you have backfires, especially on older systems, you can blow out your catalytic converter or muffler. Then when driving the chunks can block the exit pipe and cause a restriction, which can lead to sluggish driving and stalls. Usually when its shut off, the airflow that was pushing the chunks against the exit opening stops, allowing the chunks to shift and allow airflow again until put under a load.

I did not have any back fires that I remember but you brought up a good subject! I had a 1990 Ford crew cab dually I bought brand new from the dealer. It did not have o'2 sensors. I gutted the cat in 97 after it becoming restricted. I drove that truck for 5 more years without any smog issues. The problem is that I do not remember if I had to smog it because it lied in the one ton commercial class of exempt back then! My question is can that not be done to todays cats? Maybe not gutting entirely but removing some of the levels of honey comb restrictions located inside to still allow heat but restrict less?

Well, if you want it to pass smog on the next go-round I'd leave it alone. A properly functioning cat isn't robbing you of much (any) horsepower anyway.