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Old 01-25-2021, 06:13 AM   #1
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1994 30' Excella
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Hard start from cold

454 , factory fuel injection, all new hoses, filters, external fuel pump at low point of tank.
Always used to start on the first crank, regardless of cold or hot. Now i have to turn ignition on 2-3 times to let the relay build up the pressure before it will fire up. No fuel in oil analysis (thanks Keyair for Blackstone link)

Leaky Injectors? I would say most likely fuel related. What else could I be looking at?
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Old 01-25-2021, 08:58 AM   #2
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You may want to get, rent or borrow (many autocrats stores lend some tools) a fuel pressure gauge. I'd check pressure at or near the fuel injector rail(s) and see what difference if any cycling ignition makes. There has to be some significance to that. If it is minimal, I'd suspect gummed up fuel injectors. Sea Foam does a nice job of cleaning them but there are other products also.

If pressure is variable, I'd look more closely at that new pump....
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Old 01-25-2021, 06:33 PM   #3
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Peter, I permanently installed a fuel pressure gauge on the Argosy. The pressure transducer is mounted right about the end of the intake manifold where the line comes up at the back of the engine.

Highly recommended.

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Old 01-25-2021, 08:13 PM   #4
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Thank you both! I was really hoping you tell me to just slightly tap the injector and all will be well... I suppose i will have to dig in a little deeper. Strangely enough, it changed when I replaced the fuel pump relay as preventive maintenance. Since, I reinstalled the old relay, just to rule any connection out. Its acting the same with both relays.
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Old 01-26-2021, 09:14 AM   #5
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Second for checking fuel pressure at the rail, as I noted similar slow to start performance when my regulator just failed



I even had a spare oil filled gauge but I left it in the shop and installed a transducer. Let me know if you want it, I have someone swinging by the shop this afternoon that can probably find it and get it in the mail to you
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Old 01-26-2021, 11:16 AM   #6
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It is strange that it changed when you replaced the fuel pump relay and then changed again upon replacing the relay. Can you measure the power at the cable connecting your pump relay (both up-stream and down-stream from the relay connection)? If there is a bad/failing wire and/or connector the associated voltage drop could be robbing your fuel pump of enough voltage to affect the pump's output pressure. Once enough power has heated the supply line and/or connectors (passing power through them 2-3 times) the wire and/or connector could expand making a better contact and supplying enough power to the fuel pump.
Just a thought should your other efforts not solve the problem.
Best regards,
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Old 01-26-2021, 04:41 PM   #7
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1991 25' Airstream 250
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Quote:
Originally Posted by PeterH-350LE View Post
454 , factory fuel injection, all new hoses, filters, external fuel pump at low point of tank.
Always used to start on the first crank, regardless of cold or hot. Now i have to turn ignition on 2-3 times to let the relay build up the pressure before it will fire up. No fuel in oil analysis (thanks Keyair for Blackstone link)

Leaky Injectors? I would say most likely fuel related. What else could I be looking at?
Section 2 might provide some clues.

http://www.73-87chevytrucks.com/tech...iveability.pdf
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Old 01-26-2021, 06:16 PM   #8
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You probably answered your own question.....you need a fuel gauge to get your answer. Could be the throttle body injectors, but I doubt that, most probable cause in bad fuel pressure regulator (allowing) fuel back to the tank after you shut the engine off, or a bad check valve in the pump itself, also allowing fuel back to the tank after you shut the engine off. To determine which is at fault install the pressure gauge shut engine off and clamp off the return line. If the gauge drops off by morning then the problem is the check valve in the pump. Reverse the test to determine if the regulator is faulty, youíll have to clamp the feed line off for that test. Regards, Bob
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Old 01-26-2021, 07:07 PM   #9
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Relay

If the relay does not pull in then there is a backup for oil pressure to complete the fuel pump circuit

So a quick fix is swap the AC relay for the fuel pump relay.

Another back up is GM somewhere under the hood left a wire that if given12 volts will power the pump directly 24/7

You should turn the key on no crank and with the gas cap off listen. The pump should prime for 10 seconds then turn off. If no pump you have a fuse/ relay problem

Are you using to thick a viscosity oil. I. Cold this can slow cranking speeds. Most likely you have a fuel pump failing. I assume the fuel filter has been replaced?
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Old 01-26-2021, 08:58 PM   #10
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Thanks all for the replies. Since it has been getting progressively worse, ( and yes the pump is working and yes the relay supplies power), i decided to rebuilt the throttle body. I suspect a bad pressure regulator diaphragm. I will report back in a few days.
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Old 01-27-2021, 01:45 AM   #11
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Quote:
Originally Posted by PeterH-350LE View Post
Thanks all for the replies. Since it has been getting progressively worse, ( and yes the pump is working and yes the relay supplies power), i decided to rebuilt the throttle body. I suspect a bad pressure regulator diaphragm. I will report back in a few days.
I used this kit when mine was rebuilt. I reconciled the casting number to the numbers on the ebay listing.
https://www.ebay.co.uk/itm/REBUILD-K...-/221864767173

It resolved an issue of temporary sluggishness on acceleration. It seems to contain everything you need, bar new injectors, which I tested separately.

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Old 01-27-2021, 10:24 AM   #12
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Before you rebuild a throttle body you should have fuel pressure and volume verified.
Test don’t guess
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Old 01-27-2021, 10:46 AM   #13
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Before you rebuild a throttle body you should have fuel pressure and volume verified.
Test don’t guess
I think Peter already confirmed he has a working pump and power, hence he was going to replace the diaphragm in the TB. They are prone to failure.

FYI - this doc might also be of use.
http://www.73-87chevytrucks.com/tech...TBISystems.pdf
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Old 01-27-2021, 11:34 AM   #14
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after 30 years, anything rubber or flexible makes a good first suspect
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Old 01-27-2021, 03:54 PM   #15
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When I was wrenching the throttle bodies were subject to cracking where the IAC motor Pindle seats. There was no repair because it was internal. One of the symptoms was an uncontrollable fast idle. Iíll put my 2 cents for what itís worth on a bad check valve in the new ??? fuel pump. The gauge test as I mentioned before eliminates the guess work. Regards, Bob
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Old 01-27-2021, 04:41 PM   #16
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Quote:
Originally Posted by bobmiller1 View Post
When I was wrenching the throttle bodies were subject to cracking where the IAC motor Pindle seats. There was no repair because it was internal. One of the symptoms was an uncontrollable fast idle. Iíll put my 2 cents for what itís worth on a bad check valve in the new ??? fuel pump. The gauge test as I mentioned before eliminates the guess work. Regards, Bob

Not trying to guess, just have to be able to connect a fuel pressure gauge, so I ordered an inline gauge port to connect the same.
Until it arrives, to continue our guessing game, the facts are:
It fired up on the first crank for 10 month, cold or hot with a new external fuel pump that apparently does not have an internal check valve. (Walpro GSL-392)

Now it takes progressively longer to fire it up and when i turn the key to ign on and observe the throttle body injectors, i hear a hissing sound, that appears to be a leak.
Oh, and it accelerates great and runs super.
And, I just went outside and it fired up on the second crank. So.....
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Old 01-28-2021, 06:26 AM   #17
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Quote:
Originally Posted by PeterH-350LE View Post
Not trying to guess, just have to be able to connect a fuel pressure gauge, so I ordered an inline gauge port to connect the same.
Until it arrives, to continue our guessing game, the facts are:
It fired up on the first crank for 10 month, cold or hot with a new external fuel pump that apparently does not have an internal check valve. (Walpro GSL-392)

Now it takes progressively longer to fire it up and when i turn the key to ign on and observe the throttle body injectors, i hear a hissing sound, that appears to be a leak.
Oh, and it accelerates great and runs super.
And, I just went outside and it fired up on the second crank. So.....
The hissing sound might be normal, I recall my injectors being noisy. Worth checking for vacuum leaks around the TB. However, to Bob's point, it sounds like a fuel issue and I imagine you haven't messed with the Throttle Body, so what's changed aside from the new fuel pump and its power/ground? Maybe there is crud in tank which is restricting flow?
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Old 01-28-2021, 06:46 AM   #18
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Well.....there has to be a check valve somewhere in the supply system otherwise when you cut power to the pump the fuel will always drain back to the tank. I suggest you start there. Regards, Bob
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Old 01-28-2021, 06:55 AM   #19
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Quote:
Originally Posted by Boom Sounds View Post
The hissing sound might be normal, I recall my injectors being noisy. Worth checking for vacuum leaks around the TB. However, to Bob's point, it sounds like a fuel issue and I imagine you haven't messed with the Throttle Body, so what's changed aside from the new fuel pump and its power/ground? Maybe there is crud in tank which is restricting flow?
Just had tank cleaned, new filters. Same problem before and after having tank cleaned. Like I said it coincided with me replacing fuel pump relay and continued to have the same symptoms when I reinstalled the original relay.

As far as i can tell, pressure drops after sitting for a few days, but not overnight.

As far as the throttle body rebuilt goes, it is something I wanted to do anyways, since the last person installed some cheapo injectors from Autozone. They are not even listed as a parts option at Rock Auto. I ordered some OEM ACDelcos
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Old 01-28-2021, 06:57 AM   #20
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Well.....there has to be a check valve somewhere in the supply system otherwise when you cut power to the pump the fuel will always drain back to the tank. I suggest you start there. Regards, Bob
Thanks, I am calling Walpro to find out. Odd it would work for 10 month just fine.
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