posted 02-22-2004 11:20 AM ET (US)        

A Primer on Primers
Hyperlink:
http://continuouswave.com/whaler/reference/primer.html

posted 02-25-2004 10:28 AM ET (US)            

Great Article, as usual.

One thing I am still curious about, though, and that is the propensity of riggers to want to mount the primer bulb so close to the END of the fuel line (that is, by the engine). It seems to me, intuitively, that the proper place to mount the primer bulb would be as close as possible to the outlet of the tank. This way, you are PUSHING fuel along the fuel line, not pulling it.

I had a case the other day where I could not prime the port engine on my Temptation. (The Temptation underneath the deck looks almost exactly like my Outrage with Whaler Drive did -- by that I mean that coming from the underdeck tank there are two large hoses that run to a transition plate. At this plate are bulkhead fittings that convert the fuel lines to the black 3/8" hoses that then run to the fuel-water separators and filters, and from there to each respective engine). I could pump and pump, but could never get gasoline to flow. I tried all of the usual tricks to make it work (yes, checking orientation of the bulbs, checking for air leaks, etc).

Finally turned out the easiest way to resolve the problem (which mainly showed up of the first start-up of the day) was to add a "primer" primer bulb just a few inches past the previously mentioned transition plate. This allows me to fill the separators and filters with gasoline (and not have to create a vacuum to do it) and get gasoline to the engine filter/carb/whatever with a whole lot less squeezing. I can then reach over the WhalerDrive and prime the last bulb as usual.

I would still like for someone to explain the rationale of pulling the fuel via vacuum versus pushing the fuel from the closest point to the tank.

I appreciate the indulgence.

posted 02-26-2004 09:43 AM ET (US)            

If the primer was not placed there (on these boats with no fuel disconnect at the cowling), they would have to insert a splice and put the primer somewhere else.

posted 02-27-2004 08:15 AM ET (US)            

Cf.: http://squid.law.cornell.edu:80/cgi-bin/get-cfr.cgi?TITLE=33&PART=183&SECTION=560&TYPE=TEXT

I have read most of the regulations regarding fuel tanks (see below) and I don't see a mention of a "two minute burn rule."

Cf.: http://cfr.law.cornell.edu/cfr/cfr.php?title=33&type=part&value=183

I would appreciate if the applicable federal regulation could be cited that requires double hose clamps and describes the "two-minute burn rule."

Also, all of section 33 CFR Part-183 Subpart J Fuel Systems is not applicable to outboard powered boats. I reproduce 33 CFR 183.501 (emphasis added):

[Code of Federal Regulations]
[Title 33, Volume 2]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 33CFR183.501]

[Page 851]

TITLE 33--NAVIGATION AND NAVIGABLE WATERS

CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED)

PART 183--BOATS AND ASSOCIATED EQUIPMENT--Table of Contents

Subpart J--Fuel Systems

Sec. 183.501 Applicability.

Source: CGD 74-209, 42 FR 5950, Jan. 31, 1977, unless otherwise
noted.

General

(a) This subpart applies to all boats that have gasoline engines,
except outboard engines, for electrical generation, mechanical power, or
propulsion.
(b) [Reserved]

[CGD 74-209, 42 FR 5950, Jan. 31, 1977, as amended by CGD 81-092, 48 FR
55736, Dec. 15, 1983; USCG-1999-5832, 64 FR 34716, June 29, 1999]

http://squid.law.cornell.edu:80/cgi-bin/get-cfr.cgi?TITLE=33&PART=183&SECTION=501&TYPE=TEXT

A two and a half minute period is specified in a Fire Test procedure for components of the fuel system of boats using gasoline engines (except for outboard boats) in 33 CFR 183.590

http://squid.law.cornell.edu:80/cgi-bin/get-cfr.cgi?TITLE=33&PART=183&SECTION=590&TYPE=TEXT

posted 02-28-2004 04:12 PM ET (US)            

If the primer bulb were placed upstream of the fuel/water separating filter, you could pump the primer until firm but not be delivering fuel to the engine. A blockage in the filter could be preventing the fuel from flowing to the engine, but you would not have an indication of this from the behavior of the primer bulb.

If the primer bulb is close to the engine and you have filled it with fuel by squeezing, you can be reasonably certain the engine is being supplied with fuel. If there is a blockage downstream from this point it is probably under the engine cowling.

posted 02-29-2004 09:32 PM ET (US)            

This is contrary to the "ideal" set up that JimH references in his articles. This set up also allows the line to be primed from the helm rather than at the out boards which seem safer in the event you must change lines on the tanks or a connector comes loose from the tank while underway, all that have occured at least once each season.

posted 03-01-2004 02:13 PM ET (US)            

The primer bulb is about 8 feet from the engine, and the remaining 2 feet would connect to your gas supply. This is with the the arrow on the bulb pointing toward the engine.

posted 03-02-2004 08:43 AM ET (US)            

I don't think the OMC part is "backwards"--they just make them like that.

Here is what I said in the article:

posted 03-02-2004 02:18 PM ET (US)         

Evidently, OMC does not do this, and I also remember some earlier Tempo lines that had the bulb near the tank, probably in imitation of OMC's procedures.

I know that standard procedure always puts the bulb between the filter and the engine. I would think it makes sense to draw fuel out of the filter, and push it into the engine, rather than the resistance to push fuel through the filter to the engine.

posted 03-02-2004 02:39 PM ET (US)            

When tooling along at a low RPM sometimes the engine runs out of fuel? If I proceed to pump the bulb she starts right up again. Incidently, the bulb is not flat or empty when this happens. If I'm moving, say 4000 RPM, the motor runs great and will not run out of fuel.

I have to say that the Tempo brand stuff does not really give me a "warm and fuzzy" feeling. Seems like my grandad used to buy the Tempo pre-made lines that always gave problems. I probably should have bought Quiksilver Mercury parts. My diagnostic gameplan is to take a test tank with me next weekend and bypass the main fuel tank then the water sep etc... Until I pinpoint the problem. But if any of you gurus have any Ideas they would be much appreciated.

BTW, the 24' Justice that was being used by the Coast Guard in Cleartwater, has been regretfully replaced with a Safeboat. Also, there are no more Mercury engines in the fleet either as bothe RHIB and the Safeboat have Hondas. Kinda sad.

phatwhaler out.

ps: I'm not a huge Merc fan but they do have a little more character than Hondas.

posted 03-04-2004 09:11 AM ET (US)            

Another fantastic article on fuel lines.

Jimh,
I have purchased a new primer bulb, The hook-ups are correct and the flow is correct. I did not prop the bulb up vertically. However my question for you is, is that when a primer bulb is new, and you hook it up to the engine and pump fuel to it, is there air in the bulb that you have to get out? For instance, I would pump the primer bulb, however it does not get firm at all. No leaks in the engine either.

What I did in the past was, was I took my cowel off, and flicked a little red switch (fuel/manuel start valve), and I would squeeze the bulb and it still wouldn't get firm, however I would close the valve and then the engine would crank over, sputter, then shut down. I would have to repeat the process.

I have also noted that when I would shut the engine down for a short period of time (5-10 minutes), I would have to repeat the process again.

My electric choke in the ignition (the kind where you push the key in to prime it), is broken. I have to take the boat in and get it fixed for spring, but would it constitute for my problems? Thank you for your time.

posted 03-04-2004 12:11 PM ET (US)            

I recently installed a fuel/water filter on the inner starboard side of the splash well, put in new fuel hoses and primer bulb, and installed the primer bulb before the filter, pointing upward, where the fuel line exits the tunnel. The primer bulb works like a champ and when I change the spin-on fuel filter it is very easy to prime the empty filter. I beleive that having the primer bulb in an upright position has more to do with the success of the primer bulb than any other factor, and the most feasible place is where the fuel line exits the tunnel and turns upward towards the motor.

All of this from reading the primer on primers.

Thanks Jim H.

posted 02-12-2006 12:36 PM ET (US)            

Thanks for your stuff on primer pumps - it is the most useful information I can find by a mile. I drive a diesel. The system has a primer pump on, which keeps collapsing when driving and the engine cuts out, as though it has run out of fuel. It happens every few days and is completely at random. The primer stays collapsed even when the engine has cut out and has been left for a frew hours. This means that fuel is not filling the primer from the tank suggesting a blockage. I've had the fuel lines blown through, changed the primer twice, replaced the filter, changed the tank and sender unit, changed the breather pipe and left the fuel cap off and still the problem persists. I've also looked for a separate check valve in the system but can't find one. The problem definitely suggests a fuel supply problem, but as far as I can see I've done everything I can. Does anyone have any more ideas on what it could be. I'm completely baffled. I'm pretty sure it couldn't be the injector pump because that wouldn't explain hy the primer stays collapsed after the engine cuts out. One other thing - if I let air into the system upstream of the primer so that the primer regains its shape, then close the system again, and prime the pump a few times, the engine runs again! Bizarre! Help!

posted 02-13-2006 12:15 AM ET (US)            

I have observed that the primer bulb on my outboard's oil system will get extremely hard--so much so that I thought the bulb had itself become rock hard. It had not, it was the oil filling the bulb.

Also, on hot afternoon last summer my motor's reluctance to start caused me to become rather energetic about squeezing the primer bulb. So much so, in fact, that I precipitated a leak in the fuel system. The leak was actually due to a faulty component, which completely failed shortly afterwards. I believe it is possible to over-prime the fuel system, particularly in motors with carburetors. Extra fuel pressure will lead to the fuel eventually overflowing the carburetor float bowls. Motors with fuel-injection are not quite as easily vented to the atmosphere and will allow more pressure to be accumulated in the fuel supply line.

posted 02-13-2006 09:18 AM ET (US)            

Timberry, try using one of those hand vacuum pumps at various points to draw fuel through your system. You may be able to blow air back through the line, but if there’s a blockage, say, at the tank screen, then it may be acting like a check valve and (intermittantly) not allowing fuel flow in the desired direction. I’ll bet if you work your way back from the filter, you’ll find the blockage.

posted 08-12-2009 01:04 PM ET (US)            

He's got an immaculate mid 80s outrage with a 2006 Etec 225 on it. The bulb appears on the line going up and into the Racor filter, just above where the cables, etc, appear from the conduit and up onto the deck (on the starboard side). So his bulb is actually before the filter, and far before the motor.

posted 09-20-2010 02:20 PM ET (US)            

I found the following sentence at the beginning to be a bit misleading => "This pump (diaphragm fuel pump) has limited capacity to lift fuel from the fuel tank". Make no mistake: as it is a volumetric pump, it is actually the best pump to do this job. It will overcome the suction line resistances without any problem. Even if your suction line is completely dry and your fuel tank is located all the way in your bow.

The real issue with this pump is the fact that it only starts to operate when you crank the engine. This is too late. This means it will take a while [until] you get the proper fuel supply at the carburetors. If it would be possible to start up your fuel pump a bit earlier than cranking, there wouldn't be a problem whatsoever, and your engine would start right away. The time difference problem is exactly what you solve while priming the primer bulb. You fill up the fuel lines and fuel is almost immediately available at the carburetors. If you have an external fuelpump, like me, which you can start before the actual cranking, there is no time difference problem and off course no extra primer bulb is needed.

[Changed topic to discuss fuel pumps and how air passes through them. Please start a new thread in REPAIRS/MODS for this topic. Thank you--jimh.]

posted 09-20-2010 06:06 PM ET (US)            

There is no "issue" with a fuel lift pump, real or otherwise. The operation of the pump from engine vacuum is a known limitation of the fuel pump. If you will refer to the article, the introductory paragraph mentions this in its third sentence:

"...[the fuel pump] only begins to function with much efficiency after the engine is running."

I disagree that the pump can overcome any suction resistance in the line. I suspect that pump output volume will decrease if there is too much vacuum in the input line. In the OMC outboards there is a vacuum operated switch which monitors for excessive vacuum in the fuel line at the lift pump input. If vacuum were of no concern, I cannot imagine why a sensor would be provided to warn when the vacuum is too high.

posted 09-24-2010 01:34 PM ET (US)            

http://s860.photobucket.com/albums/ab169/N37766/Primer%20Bulb/

There are no check valve springs, just the initial pressure or vacuum when you squeeze the bulb causes them to seat. I don't know if all of the bulbs are like that or not but I suspect that both Mercury and tempo are because you can hear the valves click when you rotate a new bulb.

Bill