Odd and Even Banks on Northstar

[BodybyFisher]

Mike,

I would replace the inline fuel filter before I did anything else.

If the owner got one tank of contaminated fuel, it could be partially plugged. It does not matter if the filter was changed last year or last month.

A partially plugged filter would still allow the pressure to be read, but the restriction may contribute to the lean conditions that you describe.

I would do this first as it is relatively cheap and easily changed.

I had a similar problem on my '94 SLS Nstar. When I removed the inline filter, I found that it was full of fine sand.

Take Care,

Britt

Thanks Britt, you read my mind, before I go to the trouble of dropping the tank my plan is to swap the fuel pressure relay to see if that makes any difference then change the fuel filter, if no difference and if I see no kinks in the fuel line, I plan to drop the tank. I will post photos of the process, I don't think we have ever seen photos of a fuel pump change, thanks

I have a new gage and will recheck the pressure again today and post the results

[JimD]

Four days later, what have you discovered??

[BodybyFisher]

Ok today I checked the fuel pressure with a new gage

Key on 34

Running 34

Rev Engine 29 to 30

Changed the in line fuel filter

Same results

Note, I previously changed the FPR

Cut open fuel filter, clean

While under the car changing the fuel filter, I smelled fuel, strong fuel smell. Found the fuel filler pipe rusted badly, needs replacing. None at junk yard, rock auto did not list, local Caddy dealer found one after saying it was no longer available ODD..... found one for a different year or model that works... coming in on Monday

About the rusted fuel filler pipe, it is badly rusted, throughout about 2/3s of its length. The owner said that he has been having trouble filling the tank at the gas statioin as the pump keeps clicking off.... There is a possibility that the fuel filter SOCK in the tank is choked with rust... any thoughts? I also think that water/moisture can get into the tank, also negatively affecting engine performance, and Ill add dry gas to the fuel tank when I replace the pump

Ordering the fuel pump tomorrow from RockAuto. Straps for the tank and bolts look good, will update as I procede, I was delayed due to bad weather over here

[JohnnyG]

There is a possibility that the fuel filter SOCK in the tank is choked with rust... any thoughts?

Yep, what I said about 10 posts ago. As far as the water/moisture in the tank goes it will be obvious when you drop the tank. Adding dry gas won't be necessary and can be detrimental in some ways. The action of dry gas (alcohol) when mixed with water will tend to carry SMALL amounts of water THROUGH the system and into the engine. If you are dealing with enough water to cause this issue, just drop the tank and get all the crap out through a different opening. Due to the ethanol in gasoline today, If excessive water gets in, the fuel "phase separates" leaving an nonburnable mixture of alcohol and water in the tank. One "quality" that this mixture exhibits is its ability to suspend and hold rust and dirt particles where they can accumulate and do the most harm. Everyone really hates to drop the fuel tank, in fact I sold my '84 for the same reason, and the new owner dumped about $400.00 in new parts into it before dropping the tank and fixing the problem. In this case I think it should be next on your list especially since you need to change the filler pipe. Think about this, if fuel can get out of the filler neck, water can get in.

One more thing. IF you do find a sock filter in your tank, and it needs to be cleaned, DO NOT use any kind of detergent or soap on it, use gasoline or kerosene (safer) to clean it. The sock is likely a fine mesh nylon which relies on surface tension to keep water out of your fuel system, any detergent will destroy that action.

[BodybyFisher]

Thanks Johnny, I appreciate your input

I am going to have him run the tank down as far as he can before we do this job. If I must drain and flush or clean the tank, I am a little concern as to how I would do that safely.

Don't shoot me but what do you think about this thought, I have a sealed Little Giant pump that I used to empty my Jacuzzi and fish tank, can I use that to empty the tank or is this a hand pump situation? But I guess now that I think about it, I could pour it out of the fuel inlet also

Empty, the tank is equally as dangerous correct?, how to get rust out if there is any?

[JohnnyG]

Don't shoot me but what do you think about this thought, I have a sealed Little Giant pump that I used to empty my Jacuzzi and fish tank, can I use that to empty the tank or is this a hand pump situation? But I guess now that I think about it, I could pour it out of the fuel inlet also

Empty, the tank is equally as dangerous correct?, how to get rust out if there is any?

Other than the fish/bathers not liking that idea very much........?

Don't use any kind of electrically operated pump unless it is certified for use in flammable service and intrinsically safe. Same thing goes for any extension cords, flashlights, and any surrounding equipment or flames that might cause a spark. That rules out pressure washers, etc. Also be mindful of static electricity while your working near flammable liquids. Once the gas tank is empty, it now can contain an explosive vapor mixture, so yes it is still dangerous and possibly more dangerous. Just use the pour out option and catch the fuel in a large drip pan. Move the pan away from your work area, to a safe secure location.

You shouldn't need to completely gas free the tank to do the work though just get the tank empty and in a safe area and remove the fuel pump/filter assembly. Take it to a nearby location to work on it, once in open air most of the gasoline will evaporate quickly. Use a hand held mirror to direct sunlight into the openings of the tank in order to inspect it internally.

At this point, if you need to clean the inside of the tank, most people will just use a garden hose or steam to finally get all of the gasoline and vapors out, air can also be used but go easy with it. Blasting air from a hose can cause a static spark! Repeated flushing with kerosene or var-sol (a non-flammable solvent) would also be effective here, but crate more waste. If you use water (the cheapest option) be mindful of where the runoff ends up........it could contain gasoline and you don't want that on the ground or in a stream. Oil absorbent material or cotton (non sparking) rags can be used to effectively mop out and trap any fuel and can be incinerated after the job is complete.Dispose of all waste correctly. Finally, a few flushes with 92% isopropyl alcohol will get the water out. A local garage should have disposal options for the liquid waste gasoline mixture.

I hope you are dealing with a plastic tank, that way it won't be rusted inside. If it turns out to be a metal tank, you'll need to evaluate its condition....it might be time to replace it too.

[JohnnyG]

OH yeah, and check the support straps for rust as well.

[BodybyFisher]

Hmmm, I really hope I dont need to drain the tank, that will be a nightmare. I may need to buy a 5 gallon container to pour the fuel into. I was thinking that I shouldnt do this job near the house, It is a plastic tank. Thanks Johnny,

[JohnnyG]

You know, we've been focusing on fuel delivery, but did you ever consider that the CAT is plugged? I know you said it was rattling but was probably the heat shield, and I know that a miss from a plugged CAT shouldn't be noticable during idle, but neither should low fuel pressure. Both of these misses should only be apparent under load.

Forgive me if I'm missing a post, I started re-reading the whole thread and stopped when I had this idea.

[JohnnyG]

Well, I know (now, after more reading) you considered that the CAT might be plugged, I should have said "Did you ever rule it out"?

[BodybyFisher]

Well, yes, the fuel pump pressure test caused me to look at the pump as the cause, but the CAT has not been scratched off the list yet, until the fuel pressure is up to spec. I have not heard the CAT rattling yet, the owner told me that.

[Cadillac Jim]

Trust me, if the cat gets bad enough it will cause sluggish performance off-idle or even idling problems (it got that bad for me once with my Quad 4 HO). If the cat is bad and rattling, it likely has a cracked or broken ceramic element and the flow of exhaust is passing pieces of ceramic down to the mufflers, clogging them (as happened to me with the Quad 4 HO). If the cat is rattling, the sooner it's replaced, the better, whether or not the exhaust is clogged yet.

A cat can be clogged by engine problems such as excessive oil burning, excessive and continued misfiring, and burning or passing coolant through the exhaust, but these problems won't cause rattling. If the engine runs OK at low RPM, it's best to fix the engine problems before replacing the cat, of course.

[JohnnyG]

Let's look at it this way. We all like to have an orderly diagnosis that takes us down a predetermined path, but sometimes that path has a branch that must be explored.

If you NEED to drop the tank to change the filler neck, that's one thing. You can check for issues with a sock filter (if one exists) and fuel pump at that time, but in the meantime, it would be a good idea to just separate the exhaust system ahead of the CAT just to make sure the exhaust is not plugged in some way. Electrical parts are usually returnable if the box HAS NOT BEEN OPENED. If you catch my drift.

[BodybyFisher]

Johnny, you don't think that 30 PSI on acceleration is low?

[Cadillac Jim]

The fuel pressure should go down on idle, up on acceleration, tracking the vacuum. The only absolute number is the highest pressure that the FPR will allow, which is with the engine not started and manifold vacuum zero, which should be 44 to 48 psi. Start the motor, and it should go down by the same amount as the manifold vacuum; if you are running 20 inches or about 10 psi of vacuum, the fuel pressure in the rail will be 10 psi lower, or 34 to 38 psi. When you accelerate and have only a few inches of vacuum, the pressure in the fuel rail should *increase* over the pressure at idle and be only a few psi lower than the peak reading with the engine off.

[Texas Jim]

^^^^^^^^ What he said....

[adallak]

These are my number for LT1 engine. Northstar should be pretty close. 43 PSI primed, 36 idle, 45 w/o FPR (pulled the vacuum line off), 35-41 while driving.

[KHE]

My money is on the fuel pump...

[Logan]

We talked about the pump PSI several pages ago..different GM fuel/intake systems will use different pressures. There is no such thing as a generic rule-of-thumb system pressure.

My vote is bad pump or leaking coupler.

[BodybyFisher]

Thanks Logan, I ordered the Fuel Pump and filler pipe today, will come back when the parts come in and continue this thread. I may ask that the heading is changed to 95 Eldorado - Fuel Pump / Filler Pipe R&R and Ill create a pictorial of this job

[JohnnyG]

Of course I think 30 psi is low. Whether it's the only problem, or one that can be solved by cleaning an in tank filter, that's something else. All I'm suggesting is not to open the fuel pump box until you explore the other 2 issues. In this case, exploring the possibility of a plugged CAT with the current old parts still in place would tell you how much of an improvement might be had, if any. It seems to me the separating the exhaust system ahead of the cats might be pretty easy. And it would be handy to have a fuel tank attached to the car for a test drive.

[JohnnyG]

OH yeah, it just occurred to me that a plugged exhaust can impact engine vacuum, so as Jims_97 post indicates, if fuel pressure tracks engine vacuum then it may be possible for it to also impact fuel pressure.

[BodybyFisher]

Thanks Johnny, its on my list to check out, it is easy to break the cat from the exhaust. But the first thing is to fix the fuel filler pipe and get the fuel pressure up to spec.

[JohnnyG]

So mote it be.

[BodybyFisher]

So mote it be.

Hmm, I had to look this one up, I had never hear the expression! Are you a Freemason?

In the 24th Century it was modified to "Make It So" and it becomes Captain John Luke Picards favorite saying

http://en.wikipedia....i/So_mote_it_be

I am actually looking forward to doing this job, its challenging but not too challenging unless I blow myself up . TexasJim called me to give me a 5% discount for Rockauto and even though I had already completed the order, they credited me with the discount so it more than paid for the shipping. Thanks Jim

The pipe is on back order from Cadillac, it was suppose to be in yesterday and now it wont be in till next week, amazing. The fuel pump that I ordered at 1 PM today from ROCKAUTO already shipped.... I ordered the Delphi unit, its cheaper than the AC DELCO but not as cheap as the Carter or Spectra units.

While I am under the car, I need to look over the leveling system, his "mechanic" added a MANUAL fill valve to the system but he failed to realize that the bladders on the shocks leaked. amazing.

Did someone hear my calling, I think I missed it..... (especially when I see mechanics that short cut and misdiagnose)