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69 Thunderbird | 90 Seville | 03 Corolla | 89 Marquis(scrapped) | 72 Torino(scrapped)
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Discussion Starter #1
Since Ive owned my 90 Seville, I've gotten intermittent hard starts(longer cranking) when the engine is hot. It only happens once in a while. There's no sign of fuel at the FPR nipple under any conditions and I just changed all eight injectors to Bosch III's and they dont leak. The entire ignition system is in perfect order and has less than 10k miles on it. Pretty much every maintenance part has less than 15k. I always figured my old injectors were leaking but after putting in the new ones the hard start still happens sometimes. What else could it be?

EDIT: No ECM codes btw.
 

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1995 FWB 128,*** miles
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2,277 Posts
Fuel pressure guage would help. Is the Ignition Control Module original? I believe if cranking takes too long ( do not know how long exactly) a trouble code will be set.
 

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69 Thunderbird | 90 Seville | 03 Corolla | 89 Marquis(scrapped) | 72 Torino(scrapped)
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2,026 Posts
Discussion Starter #3
Fuel pressure guage would help. Is the Ignition Control Module original? I believe if cranking takes too long ( do not know how long exactly) a trouble code will be set.
The module is as new as the rest of the system. I replaced everything chasing E041 which turned out to be the computer....

I dont have a fuel pressure gauge. I might pick one up just to check. I could see it being caused by less than adequate pressure, but then again why would it be intermittent?:hmm: The level in the tank has no effect on it. Usually it happens after I make a quick stop like when leaving the convenience store... Yesterday it happened at the bank. Its never happened on a cold startup ever.

I wonder if the FPR can leak internally?
 

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'85 Fleetwood FWD
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728 Posts
Did you replace the coil also ?? Have someone crank it when it wont start, while you check for how good the spark is.
You could also try some starting fluid, and if that helps you may have a fuel problem, unless it's flooded instead of too lean.
Just some ideas.......
 

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69 Thunderbird | 90 Seville | 03 Corolla | 89 Marquis(scrapped) | 72 Torino(scrapped)
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2,026 Posts
Discussion Starter #5 (Edited)
Yeah coil too. Both of them. Every piece of the ignition system besides the bare distributor body itself is under 10k mi. Autolite platinums gapped at 0.60", 93 Shell gas exclusively, new fuel filter, the whole works. I had this issue before I replaced the ignition system... or anything else for that matter.

The car ALWAYS starts btw (Knock on wood) It just takes quite a bit longer cranking sometimes and ONLY when hot. Usually the first thing to check is a leaking FPR or dripping injectors. Neither are an issue unless the FPR leaks internally into the return line, causing the rail pressure to be too low.... right?:bonkers: ... or not gong into the return enough causing pressure to be too high resulting in too much fuel at start? :hmm:

I cant make the condition happen in my garage where I can check things unfortunately... Guess I'll have to do the old gauge to the windshield method. I'll have to pick up a gauge this weekend... Is there any way to check the FPR for internal leakage?

The way I see it, If the FPR leaks too much fuel into the return, The pressure at the rail will read low and make it look like the pump is going bad.

:bighead:

Another thought: At what operating condition does the FPR start to release fuel into the return? I assume it doesnt do it all the time or else the pump would run constantly with the key on, engine off. But what about at idle? Would I get an accurate reading from the pump at idle regardless of whether or not the FPR leaked internally?
 

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1992 Sedan Deville, 1984 Lincoln Town Car
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759 Posts
This may seem ludicrous, but yet possibly practical since you have replaced everything but the FPR. It seems obvious that you are somehow losing fuel pressure or there is more than enough to go around and the engine is flooding when it's too hot. so why mess around with the pressure gauge? Just save the money and apply it toward the new FPR. If the FP measured low or high or normal, you will still have the problem, right? Spark seems to be there since the car always starts. so...why pay more? for a gauge that you will use only once to tell you what you already have a clue about?
 

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69 Thunderbird | 90 Seville | 03 Corolla | 89 Marquis(scrapped) | 72 Torino(scrapped)
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2,026 Posts
Discussion Starter #7
This may seem ludicrous, but yet possibly practical since you have replaced everything but the FPR. It seems obvious that you are somehow losing fuel pressure or there is more than enough to go around and the engine is flooding when it's too hot. so why mess around with the pressure gauge? Just save the money and apply it toward the new FPR. If the FP measured low or high or normal, you will still have the problem, right? Spark seems to be there since the car always starts. so...why pay more? for a gauge that you will use only once to tell you what you already have a clue about?
Yeah, that makes sense. Either the FPR or the pump is on its way out. I sure would like to know which one though. I dont want to buy both.
 

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69 Thunderbird | 90 Seville | 03 Corolla | 89 Marquis(scrapped) | 72 Torino(scrapped)
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2,026 Posts
Discussion Starter #9
The pump wont be temp sensitive though, like the fuel rail.
Hmm, thats a good point.... You'd think if it were the pump, I'd get at least one hard cold start but that has never happened. DUH!! Must be the FPR! :highfive:

Autozone wants 75 bucks for the thing! Outrageous.
 

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1992 Sedan Deville, 1984 Lincoln Town Car
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759 Posts
Hmm, thats a good point.... You'd think if it were the pump, I'd get at least one hard cold start but that has never happened. DUH!! Must be the FPR! :highfive:

Autozone wants 75 bucks for the thing! Outrageous.
U r blessed -mine was $100+ and the fuel gauge was around that too. I know gauges r cheaper than that on the mainland, but here - middle of the Pacific, prices suck! Don't even ask what the fuel pump would cost. ***etaboutit! :cool2:
 

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69 Thunderbird | 90 Seville | 03 Corolla | 89 Marquis(scrapped) | 72 Torino(scrapped)
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2,026 Posts
Discussion Starter #11
Rockauto.com has the AC Delco part for $50 :bouncy:
 

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1992 Sedan Deville, 1984 Lincoln Town Car
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759 Posts
be sure to save the O-ring seal from your old one.
I went bonkers trying to get a new OEM one. and no one had except the stealership. Finally bought a same size one from ACE hardware, of all places, and it worked perfect for $0.15 instead of the $9+ that the stealership wanted for the one (count it, 1 ) teeny, little O-ring. they don't refer to it as stealership for nothing.
 

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69 Thunderbird | 90 Seville | 03 Corolla | 89 Marquis(scrapped) | 72 Torino(scrapped)
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2,026 Posts
Discussion Starter #13
Geez for a 50 - 75 dollar part, you'd think it would come with one. Luckily I have one of those universal o-ring sets with every imagineable size. It has come in very handy over the years...

Btw, does the fuel rail need to come up to replace it? It looks to be that way, which sucks cause I just had the fuel rail out changing the injectors.
 

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1992 Sedan Deville, 1984 Lincoln Town Car
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759 Posts
Sadly the GM engineers made it damn near impossible to get at the one torx screw that holds the FPR in place without lifting the fuel rail since it "SCREWS" (pun intended) upside down, BUT if you have a tiny 1/4" open-end ignition wrench and a real short T30 TORX bit, (the kind that fits in a driver handle) you might be able to be victorious that way. OR just drill it out and replace with a wing-nut and screw. Mine was already drilled out like that, lol! My guess is the previous owner ran into the same frustration and took a drill to it.
 

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69 Thunderbird | 90 Seville | 03 Corolla | 89 Marquis(scrapped) | 72 Torino(scrapped)
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2,026 Posts
Discussion Starter #15
I use the same sort of tool combo to adjust my TPS so if that combo works, I should be good to go... Will there be clearance to drop the FPR from the rail without lifting it? I suppose I could lift it a small amount but I'd hate to pull the new injectors from their ports.

Damnit I should have replaced it when I had the chance! DOH
 

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1992 Sedan Deville, 1984 Lincoln Town Car
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759 Posts
My 4.9L is a little bigger than your 4.5 but probly you can. You have to remove the fuel pipe inlet with the FPR there is not enough room to undo that on-vehicle.
 

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1992 Sedan Deville, 1984 Lincoln Town Car
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one more little tip, don't forget to use some "petroleum based lube" per FSM on the new o-ring. This was also quite a hunt for me to find on this 3rd world Rock, where I live. Nobody had. Finally the manager at Napa had a thought, "How bout some vaseline", he said. "that's petroleum based.!" Uh, duuuuh, brain cramp! Yes, vaseline worked great.
 

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69 Thunderbird | 90 Seville | 03 Corolla | 89 Marquis(scrapped) | 72 Torino(scrapped)
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2,026 Posts
Discussion Starter #18
I think some 10w-30 will handle it. It works for everything else, including the injectors. Sometimes I think the FSM goes a little over the top.
 

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2010 DTS
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87,413 Posts
I wonder if the FPR can leak internally?
That is where they usually leak. There is a diaphragm across the middle of it that separates fuel (under pressure) on the bottom from vacuum on the top. When the diaphragm leaks it sucks raw fuel into the intake manifold causing a rich condition. Think of a manual choke closed on a carburetor. Helps cold starts and hinders hot starts.
Another thought: At what operating condition does the FPR start to release fuel into the return? I assume it doesnt do it all the time or else the pump would run constantly with the key on, engine off. But what about at idle? Would I get an accurate reading from the pump at idle regardless of whether or not the FPR leaked internally?
The FPR is open and returning fuel to the tank at idle (high vacuum, low fuel demand). It's job is to keep the fuel pressure constant at various throttle settings. Your fuel pressure reading should be somewhat accurate even if the FPR is leaking. It usually does not leak THAT bad. If it did, you might never get the car started.
 
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