'94 Eldo Hot Starting Issue, pt.3

[Ion]

I replaced the following:

1. Fuel Pump

2. Fuel Filter

3. MAP Sensor

4. TPS

5. FPR

First start in the morning, car starts right up, or...after car has sit for extended period of time. On the other hand, after running car to store, etc, (where it has not sit for extended period of time), starter will crank excessively before engine kicks in.

CONCLUSION: fuel is leaking into valves or cylinder after shutting off. If car sits for extended period of time, backed up fuel evaporates, thus alleviating excessive starter cranking. Not allowing backed up fuel to evaporate causes extended starter cranking & black smoke.

I believe this issue lies with the injectors. After all, the Northstar has over 100K miles on it. My guess is they need to be serviced, but noone in my town does this. Can someone refer a place for me to ship them for service?

[BodybyFisher]

We have been having a discussion on injectors here > http://caddyinfo.ipbhost.com/index.php?showtopic=16389

I have been to this companies site, and Logan cited Lindertech as very knowledgable on fuel injectors, check out there site, Mike

http://www.lindertech.com/

We are VERY interested in your experience/findings post to the above FUEL INJECTOR site if you would, Thanks

[BodybyFisher]

Not sure about your 94, but typically you can pick up the fuel rail and turn the key on to pressurize the injectors and watch to see which ones are leaking, you might try that before spending the big bucks to do all of them,

[Ion]

UPDATE: I forgot to throw the throttle body into the mix. The problem lies somewhere between it and the injectors. Before I pull out the injectors and ship them off for repair, I'll have a look at the TB and see if it leaks fuel after engine shuts off.

Re: finding which injector that leaks (if TB is taken out of equation), I was advised by a local very reputable carb / injector guy, that after the injectors have 100k + miles on them, it's ill-advised to only service one of them. This would amount to then having one (serviced one) running at 100%, leaving the remaining 7 running at different effencies, ie. one @ 75%, another @ 60%, etc., thus leaving engine running like poo. If I conclude that the problem lies with injector(s), I'd ship them all off to be rebuilt.

[KHE]

How would the throttle body affect the problem? There is not an injector in the throttle body. I suspect you have a leaking injector - as BodybyFisher suggested, lift the fuel rail, turn the key to ON and watch for drips at the injectors. You may need to repeat the key ON routine a few times.

[Ion]

How would the throttle body affect the problem? There is not an injector in the throttle body. I suspect you have a leaking injector - as BodybyFisher suggested, lift the fuel rail, turn the key to ON and watch for drips at the injectors. You may need to repeat the key ON routine a few times.

I'm not a mechanic, so feel free to help me better understand the role of the throttle body. Is it's main role to regulate the mix of air to the system?

[KHE]

How would the throttle body affect the problem? There is not an injector in the throttle body. I suspect you have a leaking injector - as BodybyFisher suggested, lift the fuel rail, turn the key to ON and watch for drips at the injectors. You may need to repeat the key ON routine a few times.

I'm not a mechanic, so feel free to help me better understand the role of the throttle body. Is it's main role to regulate the mix of air to the system?

Yes - it regulates the flow of air into the mix.

[BodybyFisher]

See this site for the following FI descriptions

<a href="http://en.wikipedia.org/wiki/Fuel_injectio..._body_injection" target="_blank">http://en.wikipedia.org/wiki/Fuel_injectio..._body_injection</a>

Various injection schemes

GM Throttle Body Injection unit

Throttle body injection

Throttle-body injection (called TBI by General Motors and Central Fuel Injection (CFI) by Ford) or single-point injection was introduced in the mid-1980s as a transition technology toward individual port injection. The TBI system injects fuel at the throttle body (the same location where a carburetor introduced fuel). The induction mixture passes through the intake runners like a carburetor system, and is thus labelled a "wet manifold system". The justification for the TBI/CFI phase was low cost. Many of the carburetor's supporting components could be reused such as the air cleaner, intake manifold, and fuel line routing. This postponed the redesign and tooling costs of these components. Most of these components were later redesigned for the next phase of fuel injection's evolution, which is individual port injection, commonly known as MPFI or "multi-point injection". TBI was used extensively on American-made passenger cars and light trucks in the 1980 to 1995 timeframe.

Continuous injection

Bosch's K-Jetronic (K stands for kontinuierlich, or continuous) was introduced in 1974. In this system, fuel sprays constantly from the injectors, rather than being pulsed in time with the engine's intake strokes. Gasoline is pumped from the fuel tank to a large control valve called a fuel distributor, which separates the single fuel supply pipe from the tank into smaller pipes, one for each injector. The fuel distributor is mounted atop a control vane through which all intake air must pass, and the system works by varying fuel volume supplied to the injectors based on the angle of the air vane, which in turn is determined by the volume flowrate of air past the vane, and by the control pressure. The control pressure is regulated with a mechanical device called the control pressure regulator (CPR) or the warm-up regulator (WUR). Depending on the model, the CPR may be used to compensate for altitude, full load, and/or a cold engine. On cars equipped with an oxygen sensor, the fuel mixture is adjusted by a device called the frequency valve. The injectors are simple spring-loaded check valves with nozzles; once fuel system pressure becomes high enough to overcome the counterspring, the injectors begin spraying. K-Jetronic was used for many years between 1974 and the mid 1990s by BMW, Lamborghini, Ferrari, Mercedes-Benz, Volkswagen, Ford, Porsche, Audi, Saab, and Volvo. There was also a variant of the system called KE-Jetronic with electronic instead of mechanical control of the control pressure.

Central port injection (CPI)

General Motors developed an "in-between" technique called "central port injection" (CPI) or "central port fuel injection" (CPFI). It uses tubes with poppet valves from a central injector to spray fuel at each intake port rather than the central throttle-body. This system tends to have a high failure rate and repair is fairly easy. The 2 models used were CPFI from 1992 to 1995, and CSFI from 1996 and on. On early CPI (CPFI) systems fuel is continuously injected to all ports simultaneously also called "batch fire", which is less than optimal. On 1996 and later CSFI systems the fuel is sprayed sequentially as the name implies "Centralized Sequential Fuel Injection".

Multi-point fuel injection (this is what the NS has I believe)

Multi-point fuel injection injects fuel into the intake port just upstream of the cylinder's intake valve, rather than at a central point within an intake manifold, referred to as SPFI, or single point fuel injection. MPFI (or just MPI) systems can be sequential, in which injection is timed to coincide with each cylinder's intake stroke, batched, in which fuel is injected to the cylinders in groups, without precise synchronisation to any particular cylinder's intake stroke, or Simultaneous, in which fuel is injected at the same time to all the cylinders.

All modern EFI systems utilize sequential MPFI. Some Toyotas and other Japanese cars from the 1970s to the early 1990s used an application of Bosch's multipoint L-Jetronic system manufactured under license by DENSO.

Direct injection (current NS uses this)

Many diesel engines feature direct injection (DI). The injection nozzle is placed inside the combustion chamber and the piston incorporates a depression (often toroidal) where initial combustion takes place. Direct injection diesel engines are generally more efficient and cleaner than indirect injection engines. See also High-pressure Direct Injection (HDi).

Some recent petrol engines utilize direct injection as well: BMW, Ford(DISI), GM, Lexus, Subaru, Mazda(DISI), Mitsubishi(GDI), Saab, Saturn, Volkswagen and Audi (FSI) (for Fuel Stratified Injection). This is the next step in evolution from multi port fuel injection and offers another magnitude of emission control by eliminating the "wet" portion of the induction system. See also: Gasoline Direct Injection

Maintenance hazards

Fuel injection introduces extra hazards in engine maintenance due to the high fuel pressures used. Residual pressure can remain in the fuel lines long after a car has last been used, which requires care to catch any spray when disconnecting a fuel hose. If a high-pressure diesel fuel injector is removed from its seat and operated in open air, there is a risk to the operator of injury by hypodermic injection.

[Ranger]

Remove the manifold cover and lift the fuel rail. Turn the key on to energize the fuel pump and pressurize the fuel system. Look for a leaky injector.

[Logan]

I'm surprised. No mention of a failed fuel pressure regulator?

Pretty common issue.

Saw one once on a Olds Quad 4. Complete failure. It was like having a wide open fuel line running into the vacuum line. Red hot exhaust manifold.

*UPDATE: I see now the FPR was replaced..

Some other ideas..

Always using high 93 octane? See this on Corvettes often. This can 'soot' up an engine with carbon deposits. Try some full throttle (WOT) passes.

Carbon build up on the valves. Will soak up the gasoline. See WOT.

Next time, try holding the gas petal 1/4 while starting. If it starts OK. It would indicate a problem with the ISC or adjustment.

[Ranger]

I almost fell into the same trap Logan. Had the response all typed out and went back and reread it before I replied.

[jackc]

Remove the manifold cover and lift the fuel rail. Turn the key on to energize the fuel pump and pressurize the fuel system. Look for a leaky injector.

Sadly, he can't do this on a 94 - Everything's inside the manifold/plenum box...

The new FPR sounds suspect to me. I recently got a GM FPR that was bad right out of the box. Can you swap the old one back in and see if the problem goes away?

Also - were the fuel rail o-rings replaced while it was apart? There's one on the fuel inlet side that would not come with a new FPR. Could have some seepage there. Any leakage on a 94 will be inside the manifold and can cause a hot hard start.

[Ion]

Logging back in to see if anyone has feedback about injectors. I am going to replace all of mine and am trying to determine if re-built, like what this company (lindertech.com) is offering is worth the "risk"? I'm hearing about a 50/50 mix re: new vs. re-built and would sure like to save a substantial amount of $ by going with re-built, but surely don't want to be confronted with problems because of them.

[Ranger]

Remove the manifold cover and lift the fuel rail. Turn the key on to energize the fuel pump and pressurize the fuel system. Look for a leaky injector.

Sadly, he can't do this on a 94 - Everything's inside the manifold/plenum box...

The new FPR sounds suspect to me. I recently got a GM FPR that was bad right out of the box. Can you swap the old one back in and see if the problem goes away?

Also - were the fuel rail o-rings replaced while it was apart? There's one on the fuel inlet side that would not come with a new FPR. Could have some seepage there. Any leakage on a 94 will be inside the manifold and can cause a hot hard start.

Sure he can. When I said "Remove the manifold cover"

I did not mean the beauty cover like on the '95+ engines. I meant the manifold cover that gives access to the inside of the manifold.

[jackc]

Sure he can. When I said "Remove the manifold cover"

I did not mean the beauty cover like on the '95+ engines. I meant the manifold cover that gives access to the inside of the manifold.

Well - I take my hat off to anyone who can successfully do this with a 93 or 94. Between not being able to see anything inside the box and/or having injectors shoot off of the pressurized rail when I lifted it up, I got nowhere when I tried this.

But in the end, swapping out the injectors did solve my hot hard-start problem.

[Ranger]

Maybe I am not explaining it clearly enough. You open up the manifold by removing the cover to get at the injectors (then you can see them). The injectors should be attached to the rail with a retainer of some sort, so they should not shoot off.

[jackc]

The injectors should be attached to the rail with a retainer of some sort, so they should not shoot off.

Mine doesn't have any retainers. The intake cover holds them in sandwich-style. The plastic plate that serves as the cover gasket and fuel-rail holder is also pretty wide so all I could really see is the intake runners. I could try to peek down in, but its dark and I couldn't see much. So then I started thinking, ok, how can I mount all of this stuff to a board outside of the car and pressure it up to see the injectors. But then I swapped my old injectors back in and the problem went away. So I called the vendor, told 'em one or the rebuilt injectors was leaking and they took the set back. Problem solved, excpet that I still have the original injectors.....

Ion - sorry if I'm junking up your thread.....

[Ranger]

The intake cover holds them in sandwich-style.

OH, now I understand. I thought the set up was similar to the '95+, just inside the manifold. Sure makes testing for a leaky injector rather difficult.

[jackc]

[sure makes testing for a leaky injector rather difficult.

It really does.

[chullend]

I replaced the following:

1. Fuel Pump

2. Fuel Filter

3. MAP Sensor

4. TPS

5. FPR

First start in the morning, car starts right up, or...after car has sit for extended period of time. On the other hand, after running car to store, etc, (where it has not sit for extended period of time), starter will crank excessively before engine kicks in.

CONCLUSION: fuel is leaking into valves or cylinder after shutting off. If car sits for extended period of time, backed up fuel evaporates, thus alleviating excessive starter cranking. Not allowing backed up fuel to evaporate causes extended starter cranking & black smoke.

I believe this issue lies with the injectors. After all, the Northstar has over 100K miles on it. My guess is they need to be serviced, but noone in my town does this. Can someone refer a place for me to ship them for service?

Sounds like the EGR valve.

[Ion]

I replaced the following:

1. Fuel Pump

2. Fuel Filter

3. MAP Sensor

4. TPS

5. FPR

First start in the morning, car starts right up, or...after car has sit for extended period of time. On the other hand, after running car to store, etc, (where it has not sit for extended period of time), starter will crank excessively before engine kicks in.

CONCLUSION: fuel is leaking into valves or cylinder after shutting off. If car sits for extended period of time, backed up fuel evaporates, thus alleviating excessive starter cranking. Not allowing backed up fuel to evaporate causes extended starter cranking & black smoke.

I believe this issue lies with the injectors. After all, the Northstar has over 100K miles on it. My guess is they need to be serviced, but noone in my town does this. Can someone refer a place for me to ship them for service?

Sounds like the EGR valve.

Exhaust Gas Recycle Valve is NOT the source of the problem. For one thing it was replaced a couple years ago, furthermore, a faulty EGR would not cause fuel to leak into the cylinders after shutdown, causing flooding, extended cranking, black smoke, etc, upon hot starts.

[PAUL T]

[sure makes testing for a leaky injector rather difficult.

It really does.

Jack, I have had my injectors out of my 94 Concours. They are fit in a plastic retainer that is also the intake manifold cover gasket that just snaps up and out once you loosen the wiring harness. I thought mine were fairly easy to check.

[jackc]

Jack, I have had my injectors out of my 94 Concours.

They are fit in a plastic retainer that is also the intake manifold cover gasket

Yes - the fuel rail......

that just snaps up and out once you loosen the wiring harness.

Yes - but lifting the fuel rail out of the manifold box also unplugs it from the fuel lines.....

I thought mine were fairly easy to check.

OK. my experience was quite different. I tip my hat to you......

[Jan Olsson]

Jack, I have had my injectors out of my 94 Concours.

They are fit in a plastic retainer that is also the intake manifold cover gasket

Yes - the fuel rail......

that just snaps up and out once you loosen the wiring harness.

Yes - but lifting the fuel rail out of the manifold box also unplugs it from the fuel lines.....

I thought mine were fairly easy to check.

OK. my experience was quite different. I tip my hat to you......

I had the same type that you have on my -93. The cover holds the entire fuel rail in place so its dangerous to pressurise when cover is off i.e. spraying fuel on hot parts and/or near fire/ignition sources etc.. One approach could be (with cold engine of course) to have someone to turn the ignition on long enough to build up pressure (don't even think of starting the engine as it will go full throttle with this setup!) while you hold the rail down with some clamping device..don't need that much force since the area of the pipe is quite small, hold the pipe steady just in case the pipe slips.. Then gently pull up the rail long enough to see if there is dripping from some injector.

But...the best approach would be to use your invaluable AC-control panel combined with the instrument cluster. I guess you are familiar with pulling codes? In that case this won't be much harder. There is a test called "cylinder balance test" where you deactivate one cylinder at the time to track down a weak/not working cylinder. That way you could reasonably fast find out which cylinder is missing. If that don't help there is an injector leakdown test.

In that test you (with engine shut off) fire each injector individually and can measure the pressure difference in the fuel system before and after to find out if an injector is clogged or leaking. Don't have to do anything else than to connect a fuel pressure meter to the schraeder valve on the fuel line.

In your case though it seems like you have excessive amounts of fuel in the entire system for starters..on every cylinder which means back to the FPR. Don't have any codes for the idle speed control motor?

[jackc]

quote name='Jan Olsson'

I had the same type that you have on my -93. The cover holds the entire fuel rail in place so its dangerous to pressurise when cover is off i.e. spraying fuel on hot parts and/or near fire/ignition sources etc..

I hear you.....

One approach could be (with cold engine of course) to have someone to turn the ignition on long enough to build up pressure (don't even think of starting the engine as it will go full throttle with this setup!) while you hold the rail down with some clamping device..don't need that much force since the area of the pipe is quite small, hold the pipe steady just in case the pipe slips..

Did that.......

Then gently pull up the rail long enough to see if there is dripping from some injector.

Did that too..... Can't see squat inside the dark box...... Lift it up high enough to see and it unplugs the fuel rail from the fuel lines.

But...the best approach would be to use your invaluable AC-control panel combined with the instrument cluster. I guess you are familiar with pulling codes? In that case this won't be much harder. There is a test called "cylinder balance test" where you deactivate one cylinder at the time to track down a weak/not working cylinder.

Yes - My favorite test......

That way you could reasonably fast find out which cylinder is missing.

Right, but we're trying to find a leaking injector.....

If that don't help there is an injector leakdown test.

OK, sounds promising.....

In that test you (with engine shut off) fire each injector individually and can measure the pressure difference in the fuel system before and after to find out if an injector is clogged or leaking. Don't have to do anything else than to connect a fuel pressure meter to the schraeder valve on the fuel line.

Sounds good, but there are 8 injectors, 8 injector to fuel rail o-rings, an FPR, and an inlet o-ring that are possible leak points. The question is which one......

In your case though it seems like you have excessive amounts of fuel in the entire system for starters..on every cylinder which means back to the FPR.

... or the 8 injector o-rings, or the inlet o-ring - all of which will leak into the manifold box, not to mention that just one dripping injector will also make for a hard hot start......

All of which led me to thinking that the only way I could figure out exactly what was leaking was to pull the whole fuel rail/injector/fpr assembly out of the car, lash it down so the injectors wouldn't blow-off, and hook up pressurized fuel. Lets see - a board, some eye bolts, some fuel line, how do I pressurize it.... But then I said screw it - I'll put the old injectors back in and see what happens. And the hard start went away. So I said ok - lets just gently button it up, return the re-man injectors as defective, and go on with life.

Anyway - I really do envy anyone that can find a leaking injector on a 93-94. I was really wishing my car was a 95-up when I was in the middle of this. How nice to be able to just see the fuel rail and lift it up for a peek under the injectors