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Jamesbon
01-30-2001, 12:25 PM
Fellas,
After lurking in the shadows of the registry, I'm back!

So I had the GT out last weekend and am thoroughly perplexed by this one. If you recall, I'm running a Q-Jet, GM fast burn heads, 10:1 compression, .540 lift roller cam, Unilite L.E.D. distributor and 388 cu. in. When accellerating to full throttle for the first time (first time = the first time that day I wound her up tight) I can pull 5500 rpm's easily. Then once I back down cruise a while and hit it again, I rarely go above 4900 or 5000 rpm's. There's no popping or misfiring, I just don't get the rev's up where they were the first time. However, If I idle a while, or shut the boat down and try again, I'll get back up the the 5400 range again. Could this Q-Jet be getting sucked dry? (no pun) Or do I need another carb., like a Holley or....I also am using a stock mechanical fuel pump from a 350 Crusader inboard.

CDMA
01-30-2001, 12:40 PM
Nate, I am sorry to say this but I had the same thing on my 18. Started just like that. The problem is it keeps getting worse till the engine just won’t run. What I traced it down to is that there was crap in the tank. It would settle and I could run really hard once. However once I got on it hard once it would do just as you described. If I stopped I was good again for another run. I went through everything. The carb, fuel pump and only determined it by hooking up a portable 6 gallon o/b tank and running it through the same lines, filters and so forth. It ran great. So now the deck is off and a new tank on the way. In my pick up there was a little screen that was getting blocked. Had my tank been new I would have just pumped the tank and cleaned it but I figured it was due to be changed.

RickR
01-30-2001, 12:57 PM
Jamesbon
Have you been boating every day??

Chris is right, if you want to make sure install a pressure gauge (plumbing supply or auto parts) on the line between the pump and carb. You have changed your fuel filter already? If you have poured the fuel out and it was clean. Turn it upside down (let air get to the element) and let it dry for a few days. A good filter will not let water pass through.

3weeks till Grove City http://www.donzi.net/ubb/wink.gif

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RICKR
mailto:riggerb@aol.comriggerb@aol.com</A>



[This message has been edited by RickR (edited 01-30-2001).]

GEOO
01-30-2001, 07:36 PM
The fuel tank crap sounds like the problem. Is your tach working properly? Does your speed slow down when you don't get the rpm's? GEOO

Jamesbon
01-30-2001, 07:39 PM
CDMA,
Ouch. That's definetly logical. If all else fails, I'll plant the old 5 gallon "pill bottle" gas tank in the cockpit and plumb accordingly. Wheather I like to admit it or not, I know I'll be experiencing this sometime in the future. (My rig's 30 years old now)

RickR,
Man! I wish it was everyday!!! Besides this past weekend, the last rip on the intercoastal was Dec. 11th. (Yeah, I know, it's rough living down here)

Hmm, I'll take a look at the spin on fuel filter. Last year it was spotless, but I guess a lot can happen in a year. How's the 22 coming along? (If you've already spelled it out here, I'll do a search on your login and update my brain http://www.donzi.net/ubb/smile.gif ) Sounds like you're looking forward to Grove City http://www.donzi.net/ubb/biggrin.gif

MadPoodle,
I like your reply best for some reason! If you don't mind, I'll contact you for details on your mod. (or we can discuss them here for everyone's benefit) I assume that if I pull the top off the carb., it's pretty obvious what I'll have to do??

I've ran both Holleys and Q-Jets in my 31 years on this planet, and I'll have to say that maybe a good Holley double pumper might be a little faster, but I'll take a Q-Jet over a gas leaking a Holley ANYDAY!!!!!! They're extremely crisp, fuel efficient, and hold on when those giant secondaries kick in http://www.donzi.net/ubb/eek.gif


By the way, it's nice to be back!!!!!!!!!!!!

[This message has been edited by Jamesbon (edited 01-30-2001).]

Jamesbon
01-30-2001, 07:53 PM
GEOO,
Thanks for your input. Yeah, I'm running a new VDO tach., so I'm 99% that it's accurate. I need a new pito tube for the speedo, and I don't have a gps or any other method of measuring the speed, so.... I can just tell by the sound she makes when turning 5500 as opposed to 5000. It's just that extra seat of the pants something that tells me she's not always 100%.

I'm really on to MadPoodle's theory. If that doesn't work, I'll try a second fuel tank source. If that doesn't work, I'll scream till my face turns red, then throw a wrench through the drywall in the garage. That usually helps http://www.donzi.net/ubb/smile.gif

BigGrizzly
01-30-2001, 07:57 PM
Nate, still waiting for the envolope. I has the same problem. My 71 coesican had a screw in bung, pulled it out and took off the screen and let the big spin on filter do the work. than drained the tank and sucked up the residue from the tank with a oil sucker through the fuel guage sending unit hole. Not that bad of a job.

Randy

RickR
01-31-2001, 08:47 AM
Nate
She's back togeather. Ready for FLA USA.
Shake down cruise went well last week, hit the revlimiter @ 4800rpm. Felt like she might have gone 5000. Prop is in the shop getting cup added.

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RICKR
mailto:riggerb@aol.comriggerb@aol.com</A>

BillG
01-31-2001, 10:14 AM
Had the same problem a few years back. Mine was caused by the little sintered bronze filters in the fuel inlets on the carb. You may not have these, but it's easy to check.
Good luck
Bill G

Jamesbon
02-11-2001, 03:59 PM
MadPoodle,
Can you elaborate a little in regards to where the holes are that connect the primaries to the secondaries? I read they can be opened to .050, but they didn't offer any detail as to where/what I'll be drilling.

All,
I swapped the Q-Jet for a Holley 600 vacuum and an inline fuel pressure guage. Not sure what's wrong with the Holley but it ran like sh*t and I could smell unburned fuel in the exhaust. (Maybe a power valve??) How do you check the power valve? I also jetted it to factory specs, so..... Additionally I'm only getting about 3 lbs of fuel pressure. I guess I'll have to "easy out" the busted bronze piece in my old fuel pump and stick that one back in.

Also checked the screen type fuel filter (not bronze) in the Q-Jet, clean as a whistle. The spin on canister filter is clean too....

Gearhead99
02-11-2001, 05:05 PM
To check Holley power valve. You have to remove carb. But, don't tip it. Put it on the bench or on a "drift pin" in your vise. Remove the float bowl and jet block. If there is fuel on the inside compartment of the valve, it's bad. That is probably what is wrong. If you're going to continue to use the Holley, get one of those power valve portector kits. They cost $10 or so and install it or have it installed. It will give the power valve a fighting chance, so not to blow out so easy in the future.

BigGrizzly
02-11-2001, 06:36 PM
I had 2.5 with my clogged fuel pickup. boat now has 7-&gt;8 psi now.

Randy

Jamesbon
02-18-2001, 06:57 PM
Okay,
So, I swapped the old mechanical pump for a marine Holley hi vol. electric and regualtor set at 6 1/2 lbs. Also pulled the tank sender unit (thanks to Gene D's recommendation) and found one spotless 31 year old 60 gallon gas tank. In fact, I could see my reflection on the bottom of the half filled tank. Spotless! Wound her up all day today. The pump made a little difference, she would hit 5500 r's then steadily deteriorate to about 5K every time. I'm convinced, that the Q-Jet needs the mod. MadPoodle mentioned. (I know he's wrapped this weekend with the boat show and fishing tournament.....) It's a Quadrajet from a stock 350 Chev. Crusader. So, I've added 38 more ci's, higher compression, seriously radical cam and a rev limit way beyond the Crusaders target of 4400...Maybe the secondaries need to be richened up??

My neighbor gave me a 700 Holley double pumper which I'm sticking in the shop this week while I try to figure out this Q-Jet.....

Any comments/suggestions welcome.

CDMA
02-18-2001, 08:22 PM
James,

You might want to talk to Paul O. When he went from his 350 to the new 383 I believe he gained 500 -600 rpm just playing with the secondaries.

Chris

GEOO
02-18-2001, 09:18 PM
Nate, I was reading up on the Quadrajet's. The book liked the carb the only negative was the single float, float bowl, and needle and seat. I'll E:mail you the info. You probably already know this stuff. It sounds like the float adjustment, or too small of a needle and seat, or to low fuel preasure. Hope this article helps.
Hum, I think the pages are not in order, can you follow the page numbers? It's kind of large. Can you change your screen size? If it just all screwed up I'll send it again. GEOO

[This message has been edited by GEOO (edited 02-18-2001).]

PaulO
02-20-2001, 11:37 AM
Nate,
Run, don't walk to your local speed shop and pick up edelbrock's replacement secondary rods and retainer. Start swapping. Mine ran the best with the fatest ones. If you need the numbers (actually alpha characters) let me know. Do not run the motor with those stock rods, you are probably running way too lean!!!!
PaulO

Jamesbon
02-20-2001, 12:12 PM
Thanks Fellas. I received GEOO's info. on Q-Jet "metering." I'll give that a shot in the next couple days. I "bet'cha" that'll do it.

PaulO,
GEOO's articles contained all the p/n's. (At least the Chevrolet ones) Thanks a million guys!! Did you change anything else on your Q-Jet?

Jamesbon
02-20-2001, 06:12 PM
Pulled out the stock "CL" metering rods in all of about 30 seconds tonight. (Thank you GEOO, a million times over) "CL's" are .067 dia. and geared towards a stock type 305 or 350ci motor. GEOO's info. recommends a "CH" rod (.0567) for a 400/383 ci motor. I guess I'll stsrt there and work my way richer till the rpm's peak out. If that fails, "they" recommend trying a larger needle and seat, if that fails, I'll have to try MadPoodle's suggestion. The Holley 700 D.P. is supposed to be done tomorrow, so I'll give that at try too. WHEW!

Hopefully, we'll shoot down to Grove City for some boating with RickR and.....was it varyak or stromer???

Jamesbon
02-21-2001, 07:03 PM
Allright, so tonight I jetted up the secondaries on the Q-Jet, took her for a spin, no difference. It's gotta be the needle & seat size, float level, or the fact that I'm lacking "MadPoodle's super stealth Quadrajet modification." Next, I bolted on the fresh 700 Holley double pumper, fiddled with the primary float level, then set out for a last run in the dark. I saw 5400rpm for a half second then had to back off cuz my eyes were watering, I couldn't see the next marker, and it's dark as sh*t with no moon in sight. She's tied to the dock where she'll sit till about 7:00 AM when I wake up the neighbors and take her for another test run.

I really, really want to modify the Q-Jet and use that religiously! But for now,, we;ll see what the 700 DP can do. More in the AM!

PaulO,
Yes, please, what set did you end up using? I went from CL @ .0667" to AU @ .0527". I also have a set of CH @ .0567", but they're leaner then what I tried tonight. According to reference GEOO sent, DC and CC both @ .0300 are the richest.....

Nate

[This message has been edited by Jamesbon (edited 02-21-2001).]

[This message has been edited by Jamesbon (edited 02-22-2001).]

Jamesbon
02-22-2001, 07:55 AM
Okay Fellas, I ran about 8 full throttle passes this morning and most of the time I could hit 5400 rpm but a few times she fell off the mark slightly. However, when I threw the "ballast by pass switch," giving the coil a full 12 volts, she consistently climbed to 5400 r's. This was with the Holley. I recall Forrest saying one can by pass the ballast resistor, but Mallory's Unilite wiring diagram explicitly states that you must use this resistor. I'll contact them today and post my findings later. I'll also pick up a new hi perf. coil this afternoon.

When I first started using this engine, she was extremely hard to start when cold, so I added a ballast by pass switch for starting. WHen I start her cold, I throw the switch and she fires right up. Then once running, I flip the switch back throwing the juice through the ballast resistor.

What do you think?

RickR,
Yeah, please, just out of curiousity I'd love to know what secondary metering rods the 454 used. I ran the q-jet last night, then switched to the Holley for this mornings tests. Once I figure out my ignition dilemma, the Q-Jet will undoubtedly go back on and I'll have one spotless freshly re-built Holley 700 D.P. for sale.



[This message has been edited by Jamesbon (edited 02-22-2001).]

RickR
02-22-2001, 07:55 AM
Jamesbon
Are you changing the metering rods or the jets? Do you want me to check the metering rod sizes in the Q Jet for the 454?
BTW I'll be passing by this afternoon.


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RICKR
mailto:riggerb@aol.comriggerb@aol.com</A>