Need Csfi Help. Please!

Old Frog · June 1, 2007

1997 4.3, CSFI fuel system. 155K miles, Stock components/no mods.

Background: Intermittent no start problem fuel related which appeared to be a result of low fuel system pressure. No visible leaks. Fuel filter & pump replaced professionally. About 1 year & 40K miles later, problem reappears.

Because for the cost, I am doing the work myself. No CELs displayed. System Pressure low. About 50 PSI. Fuel pump relay & electrical system components all appear fine. Key On, Engine Off, pump cycles & pressure builds. Engine will start with a shot of starting fluid & continue to run & drive fine after that but will not restart without another shot of starting fluid. No visible kinks or restrictions in the fuel lines.

Fuel pump & filter replaced again. While I am at it, new plugs wires, cap, etc. installed. Still no start & pressure still @ around 50 PSI but will start fluid & continue to run. Return fuel line restricting valve test done (pressure to high high 60's (I did not push it higher)) indicating faulty fuel pressure regulator.

New fuel pressure regulator w/ screen & o-rings installed. Pressure now a biot higher, to 52 PSI but Engine still will not start cold, will start on fluid, run fine restart when hot. With engine running, pressure gage readings range in the mid 50's to low 60's. When the engine turns off, the system reads about 55 PSI. System holds pressure in the mid 50's for some time. Overnight, the pressure falls to 0. Key on cycling brings pressure to 52 but fluid needed to start.

I am starting to get POed by this time. Any suggestions on how to fix (other than a bit of C-4) would sure be appreciated.

Old Frog · June 3, 2007

Anyone?

Now I am wondering if it is a sensor problem @ cold start or perhaps the CSFI to MFI replacement tsb issue. From what I can tell, the symptoms do not match completely.

Jeremy WI · June 3, 2007

Anyone?

Now I am wondering if it is a sensor problem @ cold start or perhaps the CSFI to MFI replacement tsb issue. From what I can tell, the symptoms do not match completely.

Was the fuel pulse dampener replaced when the fuel pump was? I was told the 96's had a bad problem with them being faulty and leaking

Old Frog · June 4, 2007

"fuel pulse dampener" This is a new one to me. I have not heard the term before. I replaced the pump. Pressure still low so I ran the return line restriction test, pump produced up to 70 PSI. My impression was that it would go higher except the manual I am going by cautioned about damged if pushed too high. This lead me to replace the fuel pressure regulator under the upper intake manifold. In doing this, the Pressure when from about 48 to 52 PSI. Still low.

Where is the fule pusle dampener? Thanks.

Jeremy WI · June 5, 2007

Just above the fuel pump, looks a lot like a miniature brake fluid reservoir on my 96. I am sure some replaced them with a section of rubber fuel line, they were also called a pulsator

Old Frog · June 5, 2007

Jeremy WI'; Thanks for the info. I when by the parts dept. today with my VIN. The part descrition came up blank for the VIN. The parts guy was confused & said it did not make sense.

After I run the gas out of the tank, I will be going back to double check the tank & pump looking @ the connections & to check the voltage. I will look for the pulse dampener then. Thanks for the input post what I find.

Old Frog · June 8, 2007

An update. I have run about 3 tanks w/ Lucas injector cleaner through the van over the past week (Kind of hurts With current gas prices) and checked & driven around with with a Scan Gage II connected. Any way, here is the update:

- Normal cold starts are still not happening if I simply, turn the ignition on, wait for the fuel pump to cycle & crank the engine.

- However, if I "pop" the ignition (simply a quick hit of the starter letting the engine rotate a couple of times, not a prolonged fast cranking speed) several times, (usually 2 to 4), the engine will start. If I have cranked the engine, it will take up to 5 pops of the ignition to start.

- No trouble codes stored in PCM and none developed during approx 300 mi. driving w/ the Scan Gage connected. Specifically, no misfire codes stored.

- Gage shows idle steady w/ an occasional 25 to 30 +/- fluctuation. The fluctuation is not rhythmic. The RPM varies slightly @ idle.

- Scan Gage voltage readings are interesting (A new charged battery) and the reading double checked @ the battery w/ a multi meter:

When the engine is running: @ 13.8 to 14. V.

When engine has been turned off after running: @ 13.2.

When engine is off in the morning, just before cold start: @ 12.2 V

- I have noticed that (new pump): 1. The fuel gage reading is a bit off (empty occurs @ about 1/8 tank) and 2. The gage will rhythmically fluctuate with in time with the blinker flash or fluctuate when an electrical load is placed on the system.

Based upon the above, I am inclined to think:

1. There is one, or possibly more, electrical problem(s). Something is dragging the battery down overnight and proper voltage is not getting to the pump.

2. That it is not an injector problem, particularly given the absence of no stored codes, particularly no misfire codes.

Any thoughts on this are welcome as are suggestions as to where to first look. Bob

Jeremy WI · June 9, 2007

Remove and clean battery terminals, might just be corroded. They must have gotten rid of the pulsator in 97, according to rockauto, you can't just replace the pump, you replace the sending unit